Methods, apparatus and systems for performing multi-radio access technology carrier aggregation

ABSTRACT

A method of managing carrier aggregation for a multi-radio access technology (RAT) wireless transmitter/receiver unit (WTRU) is disclosed. The method may include: receiving, by the WRTU over a primary channel associated with a RAT of a first type, provisioning information for provisioning a supplementary channel associated with a RAT of a second type; establishing the supplementary channel associated with the RAT of the second type based on the received provisioning information; and wirelessly exchanging, by the WRTU, first data associated with a communication over the primary channel via the RAT of the first type, while wireless exchanging second data associated with the communication over the supplementary channel via the RAT of the second type.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority from U.S. Provisional Application No.61/419,712, filed on Dec. 3, 2010 and U.S. Provisional Application No.61/467,521, filed on Mar. 25, 2011, the contents of each areincorporated by reference herein.

FIELD OF INVENTION

This application relates to wireless communications and, moreparticularly, methods, apparatus and systems for performing carrieraggregation using multi-radio access technology.

BACKGROUND

The demand for improved network coverage, improved capacity andincreasing bandwidth for both voice and data services in wirelesssystems has led to continuous development of a number of radio accesstechnologies (RATs) including, but not limited to, global systems formobile communications (GSM), wideband code division multiple access(WCDMA), high speed packet access (HSPA), including high speed downlink(DL) packet access (HSDPA) and high speed uplink (UL) packet access(HSUPA) with their respective multicarrier counterparts, and long termevolution (LTE), including support for carrier aggregation.

SUMMARY

A method and apparatus are described for performing multi-radio accesstechnology (RAT) carrier aggregation (CA). In one representative method,a first medium access control (MAC) entity may be configured in awireless transmit/receive unit (WTRU) that is associated with a firstRAT, and a second medium access control (MAC) entity may be configuredin the WTRU that is associated with a second RAT. A plurality ofchannels associated with the first MAC entity and the second MAC entitymay be configured. The first RAT may be long term evolution (LTE), andthe second RAT may be at least one of wideband code division multipleaccess (WCDMA), high speed packet access (HSPA), high speed downlinkpacket access (HSDPA) and/or high speed uplink packet access (HSUPA).

Another representative method may manage carrier aggregation for amulti-radio access technology (RAT) wireless transmitter/receiver unit(WTRU). The method may include: (1) receiving, by the WRTU over aprimary channel associated with a RAT of a first type, provisioninginformation for provisioning a supplementary channel associated with aRAT of a second type; (2) establishing the supplementary channelassociated with the RAT of the second type based on the receivedprovisioning information; and (3) wirelessly exchanging, by the WRTU,first data associated with a communication over the primary channel viathe RAT of the first type, while wireless exchanging second dataassociated with the communication over the supplementary channel via theRAT of the second type.

In certain representative embodiments, the wirelessly exchanging of thesecond data over the established supplementary channel may include oneof: (1) wirelessly sending the second data over the establishedsupplementary channel; (2) wirelessly receiving the second data over theestablished supplementary channel or (3) wirelessly sending andreceiving different portions of the second data over the establishedsupplementary channel.

In certain representative embodiments, the wirelessly receivingprovisioning information may include receiving via the primary channelassociated with the RAT of the first type control information for theprimary channel and control information for the supplementary channel.

In certain representative embodiments, the first type of RAT may be oneof: (1) a wideband code division multiple access (WCDMA) RAT; (2) a highspeed packet access (HSPA) RAT; (3) a high speed downlink packet access(HSDPA) RAT; (4) a high speed uplink packet access (HSUPA) RAT; or (5) along term evolution (LTE) RAT.

In certain representative embodiments, the second type of RAT may be adifferent one of: (1) the WCDMA RAT; (2) the HSPA RAT; (3) the HSDPARAT; (4) the HSUPA RAT; (5) a LTE RAT; (6) a non-cellular RAT; or (7) aWiFi RAT.

In certain representative embodiments, the establishing of thesupplementary channel associated with the RAT of the second type mayinclude: determining, from the received provisioning information, one ormore carrier components associated with the RAT of the second type to beprovisioned for wirelessly exchanging the second data over thesupplementary channel; and provisioning the supplementary channel usingthe determined one or more carrier components.

In certain representative embodiments, the method may include prior toreceiving by the WRTU the provisioning information, establishing theprimary channel associated with the RAT of the first type, and theestablishing of the supplementary channel associated with the RAT of thesecond type may include establishing the supplementary channel using asingle radio resource connection to control radio resources of the RATsof the first and second types.

In certain representative embodiments, the establishing of the singleradio resource connection may include setting up a radio resourcecontrol (RRC) connection.

In certain representative embodiments, the method may include prior toreceiving by the WRTU the provisioning information, establishing theprimary channel associated with the RAT of the first type and theestablishing of the supplementary channel associated with the RAT of thesecond type may include establishing one or more supplementary channelsusing at least one respective radio resource connection for each of aplurality of different RAT types to control radio resources associatedwith the primary and one or more supplementary channels supportedconcurrently by the WTRU.

In certain representative embodiments, the method may includemaintaining the established radio resource connections that areapplicable to different sets of one or more carrier components such thatthe wirelessly exchanging of the first data over the primary channel viathe RAT of the first type, while wireless exchanging second data overthe supplementary channel via the RAT of the second type may includeexchanging respective portions of the first and second data of thecommunication over different ones of the established radio resource viathe different sets of carrier components.

In certain representative embodiments, the exchanging of the first dataand the second data may include operating the WTRU at a first frequencyor in a first frequency band for exchange of the first data and at asecond frequency or in a second frequency band that is the same as ordifferent from the first frequency or the first frequency band.

A further representative method may perform wireless communicationsusing a multi-mode wireless transmit/receive unit (WTRU) that isconfigured for simultaneous or near-simultaneous operation on componentcarriers (CCs) associated with a plurality of radio access technologies(RATs). The method may include: (1) configuring, in the WTRU, a highspeed packet access (HSPA) medium access control (MAC) entity and a longterm evolution (LTE) MAC entity; and (2) configuring a plurality ofchannels associated with the HSPA and LTE MAC entities.

In certain representative embodiments, the configuring of the HSPA MACentity and the LTE MAC entity may include integrating the HSPA MAC andthe LTE MAC to aggregate data exchanged via HSPA and LTE RATs.

An additional representative method may perform wireless communicationsusing a multi-mode wireless transmit/receive unit (WTRU) that isconfigured to for concurrent operation on component carriers (CCs)associated with a plurality of radio access technologies (RATs). Themethod may include: (1) exchanging information on a first CC inaccordance with a first RAT; (2) concurrently exchanging information ona second CC in accordance with a second RAT; and (3) aggregating orsegmenting the information exchanged via the first and second CCs.

In certain representative embodiments the method may include configuringone of: (1) a single radio resource connection to maintain the exchangeof the information on the first and second CCs; (2) a radio resourceconnection for each CC used to maintain the exchange of the informationon the first and second CCs; or (3) a radio resource connection for eachRAT used to maintain the exchange of the information on the first andsecond CCs.

In certain representative embodiments, the method may include sending,by the WRTU, a block acknowledgment associated with the second CC on thefirst CC to provide a block acknowledgment/non-acknowledgementindication associated information exchanged on the second CC.

A still further representative method may perform wirelesscommunications in a wireless transmit/receive unit (WTRU) supportingmulti-radio access technology (RAT) carrier aggregation (CA). The methodmay include allocating information on a first carrier according to afirst RAT; and concurrently allocating information on a second carrieraccording to a second RAT.

In certain representative embodiments, the second RAT may be a differentRAT than the first RAT.

A still additional representative method may perform wirelesscommunications using a multi-mode wireless transmit/receive unit (WTRU)that is configured for concurrent operation on component carriers (CCs)associated with a plurality of radio access technologies (RATs). Themethod may include allocating information on a first CC in accordancewith a long term evolution (LTE) RAT; and concurrently allocatinginformation on a second CC in accordance with a different RAT. Forexample, a first portion of a communication (e.g., first information) tobe sent by the WTRU may be allocated via resource block for a first CCand, at the same time, a second portion of the communication (e.g.,second information) to be sent may be allocated via another resourceblock for a second CC.

In certain representative embodiments, a single radio resource control(RRC) connection may be used to control radio resources of the RATssupported concurrently by the WTRU.

In certain representative embodiments, the method may includeconcurrently using, by the WTRU, one radio resource control (RRC)connection for each of the plurality of RATs applicable to differentsets of at least one CC such that the plurality of RATs may operate onthe same or different frequencies.

Another additional representative method may perform wirelesscommunications in a wireless transmit/receive unit (WTRU) supportingmulti-radio access technology (RAT) carrier aggregation (CA). The methodmay include configuring a first medium access control (MAC) entity inthe WTRU that is associated with a first RAT; configuring a secondmedium access control (MAC) entity in the WTRU that is associated with asecond RAT; and configuring a plurality of channels associated with thefirst MAC entity and the second MAC entity.

In certain representative embodiments, the first RAT may be long termevolution (LTE), and the second RAT may be one of: (1) wideband codedivision multiple access (WCDMA); (2) high speed packet access (HSPA);(3) high speed downlink packet access (HSDPA); (4) high speed uplinkpacket access (HSUPA); (5) a non-cellular radio access; or (6) a WiFiradio access.

One representative wireless transmit/receive unit (WTRU) may include: atransmit/receive unit configured to receive over a primary channelassociated with a RAT of a first type, provisioning information forprovisioning a supplementary channel associated with a RAT of a secondtype; and a processor configured to establish the supplementary channelassociated with the RAT of the second type based on the receivedprovisioning information such that the transmit/receive unit wirelesslyexchanges first data associated with a communication over the primarychannel via the RAT of the first type, while wireless exchanging seconddata associated with the communication over the supplementary channelvia the RAT of the second type.

In certain representative embodiments, the transmit/receive unitwirelessly may receive, via the primary channel associated with the RATof the first type, control information for the primary channel andcontrol information for the supplementary channel.

In certain representative embodiments, the transmit/receive unitwirelessly may exchange the first data using one of: (1) a wideband codedivision multiple access (WCDMA); (2) a high speed packet access (HSPA);(3) a high speed downlink packet access (HSDPA); (4) a high speed uplinkpacket access (HSUPA); and/or (5) long term evolution; (LTE) access;

In certain representative embodiments, the transmit/receive unit mayexchange the second data, during the exchange of the first data, usingat least a different one of: (1) the WCDMA; (2) the HSPA; (3) the HSDPA;(4) the HSUPA; (5) the LTE access; (6) a non-cellular access; and/or (7)a WiFi access.

In certain representative embodiments, the processor may determine fromthe received provisioning information one or more carrier componentsassociated with the RAT of the second type to be provisioned forwirelessly exchanging the second data over the supplementary channel;and may provision the supplementary channel using the determined one ormore carrier components.

In certain representative embodiments, the processor, prior to receivingthe provisioning information, may establish the primary channelassociated with a single radio resource connection and, after receivingthe provisioning information, may establish the supplementary channelassociated with the same single radio resource connection of the primarychannel to control radio resources of the RATs of the first and secondtypes.

In certain representative embodiments, the processor, prior to receivingthe provisioning information, may establish the primary channelassociated with a first radio resource connection and, after receivingthe provisioning information, may establish the supplementary channelassociated with a second radio resource connection to respectivelycontrol radio resources of the RATs of the first and second types.

In certain representative embodiments, the processor may operate theWTRU at a first frequency or in a first frequency band for exchange ofthe first data and at a second frequency or in a second frequency bandthat is the same or different from the first frequency or the firstfrequency band.

Another representative multi-mode wireless transmit/receive unit (WTRU)may perform wireless communications and may be configured for concurrentoperation on component carriers (CCs) associated with a plurality ofradio access technologies (RATs). The multi-mode WTRU may include: aprocessor configured for concurrent operation of a high speed packetaccess (HSPA) medium access control (MAC) entity, a long term evolution(LTE) MAC entity; and a plurality of channels associated with the HSPAand LTE MAC entities such that the HSPA MAC entity and the LTE MACentity are configured to aggregate data exchanged via HSPA and LTE RATs.

A further multi-mode wireless transmit/receive unit (WTRU) may performwireless communications and may be configured to support simultaneous ornear-simultaneous operation on component carriers (CCs) associated witha plurality of radio access technologies (RATs), The multi-mode WTRU mayinclude: a transmit/receive unit configured to exchange information viaa first CC in accordance with a first RAT and to concurrently exchangeinformation via a second CC in accordance with a second RAT; and aprocessor configured to aggregate or to segment the informationexchanged via the first and second CCs.

In certain representative embodiments, the WTRU may be one of: (1) anend user terminal; or a network access point.

In certain representative embodiments, a non-transitory computerreadable storage medium may store program code executable by computerfor implementing any representative method.

BRIEF DESCRIPTION OF THE DRAWINGS

A more detailed understanding may be had from the Detailed Descriptionbelow, given by way of example in conjunction with drawings appendedhereto. Figures in such drawings, like the detailed description, areexamples. As such, the Figures and the detailed description are not tobe considered limiting, and other equally effective examples arepossible and likely. Furthermore, like reference numerals in the Figuresindicate like elements, and wherein:

FIG. 1A is a diagram illustrating a representative communication systemin which one or more disclosed embodiments may be implemented;

FIG. 1B is a diagram illustrating a representative wirelesstransmit/receive unit (WTRU) that may be used within the communicationsystem of FIG. 1A;

FIG. 1C is a diagram illustrating a representative radio access networkand a representative core network that may be used within thecommunication system of FIG. 1A;

FIG. 2 is a diagram illustrating a representative packet data networkarchitecture supporting numerous radio access technologies (RATs);

FIG. 3 is a diagram illustrating a representative mapping of downlink(DL) logical channels to DL transport channels;

FIG. 4 is a diagram illustrating a representative multi-RAT layer 2 (L2)DL structure;

FIG. 5 is a diagram illustrating a representative medium access control(MAC)-ehs entity on an evolved Node-B (eNB) side;

FIG. 6 is a diagram illustrating a representative MAC architecture;

FIG. 7 is a diagram illustrating a representative MAC-ehs entity on aWTRU side;

FIG. 8 is a diagram illustrating a representative MAC architecture usingmulti-RAT aggregation and a common long term evolution (LTE) MAC headerformat.

FIG. 9 is a flowchart illustrating a representative method for managingcarrier aggregation for a multi-RAT WTRU;

FIG. 10 is a flowchart illustrating a representative method forperforming wireless communications using a multi-mode WTRU;

FIG. 11 is a flowchart illustrating another representative method forperforming wireless communications using a multi-mode WTRU;

FIG. 12 is a flowchart illustrating a representative method forperforming wireless communications in a WTRU supporting multi-RATcarrier aggregation (CA);

FIG. 13 is a flowchart illustrating a further representative method forperforming wireless communications using a multi-mode WTRU; and

FIG. 14 is a flowchart illustrating another representative method forperforming wireless communications in a WTRU 102 supporting multi-RATCA.

DETAILED DESCRIPTION

Spectrum is a costly resource and not all frequency bands may beavailable to all operators. Operators may offer support for both HSPAand LTE services with carrier aggregation scenarios that may typicallyuse a few component carriers (CCs) per RAT (e.g., may be limited to, forexample, at most 2-3 CCs per RAT for a particular operator). Legacydeployments may be maintained for the foreseeable future (e.g., duringand/or after LTE deployment), which may lead to underutilization ofradio resources, spectrum and capacity in one or more of the operator'sRATs.

Operators may also offer support for WiFi services e.g. in hot spotareas, using for example one or more WiFi technology such as 802.11b/g/nin the 2.4 GHz frequency band, 802.11y in the 3.6 GHz frequency bandand/or 802.11a/h/j/n in the 5 GHz frequency band.

In certain representative embodiments, methods, apparatus and systemsmay allow a wireless transmit/receive unit (WTRU) to operatesimultaneously on multiple frequencies such that the WTRU may operate onat least one of the frequencies according to a different RAT (e.g., theWTRU may operate using multiple RATs).

WTRU generally refers to, but is not limited to, user equipment (UE), amobile station, a fixed or mobile subscriber unit, a pager, a cellulartelephone, a personal digital assistant (PDA), a tablet, a computer, orany other type of user device capable of operating in a wirelessenvironment. Base station generally refers to, but is not limited to, aNode-B, a site controller, an access point (AP), or any other type ofinterfacing device capable of operating in a wireless environment.

FIG. 1A is a diagram illustrating a representative communication systemin which one or more disclosed embodiments may be implemented.

The communication system 100 may be a multiple access system thatprovides content, such as voice, data, video, messaging, and/orbroadcast, among others, to multiple wireless users. The communicationsystem 100 may enable multiple wireless users to access such contentthrough the sharing of system resources, including wireless bandwidth.For example, the communication system 100 may employ one or more channelaccess methods, such as code division multiple access (CDMA), timedivision multiple access (TDMA), frequency division multiple access(FDMA), orthogonal FDMA (OFDMA), and/or single-carrier FDMA (SC-FDMA),among others.

As shown in FIG. 1A, the communication system 100 may include WTRUs 102a, 102 b, 102 c, 102 d, a radio access network (RAN) 104, a core network106, a public switched telephone network (PSTN) 108, the Internet 110,and other networks 112, although it is contemplated that the disclosedembodiments may use any number of WTRUs, base stations, networks, and/ornetwork elements. Each of the WTRUs 102 a, 102 b, 102 c, 102 d may beany type of device configured to operate and/or communicate in awireless environment. By way of example, the WTRUs 102 a, 102 b, 102 c,102 d may be configured to transmit and/or receive wireless signals andmay include user equipment (UE), a mobile station, a fixed or mobilesubscriber unit, a pager, a cellular telephone, a personal digitalassistant (PDA), a smartphone, a laptop, a netbook, a personal computer,a tablet, a wireless sensor, and/or consumer electronics, among others.

The communication systems 100 may also include a base station 114 a anda base station 114 b. Each of the base stations 114 a and 114 b may beany type of device configured to wirelessly interface with at least oneof the WTRUs 102 a, 102 b, 102 c, 102 d to facilitate access to one ormore communication networks, such as the core network 106, the Internet110, and/or the other networks 112. By way of example, the base stations114 a and 114 b may be a base transceiver station (BTS), a Node-B, anevolved Node-B (eNB), a Home Node-B (HNB), a Home eNB (HeNB), a sitecontroller, an access point (AP), and/or a wireless router, amongothers. Although the base stations 114 a, 114 b are each depicted as asingle element, it is contemplated that the base stations 114 a and 114b may include any number of interconnected base stations and/or networkelements.

The base station 114 a may be part of the RAN 104, which may includeother base stations and/or network elements (not shown), such as one ormore base station controllers (BSCs), one or more radio networkcontrollers (RNC), and/or one or more relay nodes, among others. Thebase station 114 a and/or the base station 114 b may be configured totransmit and/or receive wireless signals within a particular geographicregion, (e.g., which may be referred to as a cell (not shown)). The cellmay further be divided into cell sectors. For example, the cellassociated with the base station 114 a may be divided into threesectors. In certain representative embodiments, the base station 114 aand/or 114 b may include three transceivers, (e.g., one transceiver foreach sector of the cell). In certain representative embodiments, thebase station 114 a may employ multiple-input multiple-output (MIMO)technology and may utilize multiple transceivers for each sector of thecell.

The base stations 114 a and 114 b may communicate with one or more ofthe WTRUs 102 a, 102 b, 102 c, 102 d over an air interface 116, whichmay be any suitable wireless communication link, (e.g., radio frequency(RF), microwave, infrared (IR), ultraviolet (UV), and/or visible light,among others). The air interface 116 may be established using anysuitable radio access technology (RAT).

The communication system 100 may be a multiple access system and mayemploy one or more channel access schemes, such as CDMA, TDMA, FDMA,OFDMA, and/or SC-FDMA, among others. For example, the base station 114 ain the RAN 104 and the WTRUs 102 a, 102 b, 102 c may implement a radiotechnology such as universal mobile telecommunications system (UMTS)terrestrial radio access (UTRA), which may establish the air interface116 using wideband CDMA (WCDMA). WCDMA may include communicationprotocols such as high-speed packet access (HSPA) and/or evolved HSPA(HSPA+). HSPA may include high-speed DL packet access (HSDPA) and/orhigh-speed UL packet access (HSUPA), among others.

In certain representative embodiments, the base station 114 a and theWTRUs 102 a, 102 b, 102 c may implement a radio technology such asevolved UTRA (E-UTRA), which may establish the air interface 116 usinglong term evolution (LTE) and/or LTE-Advanced (LTE-A).

In certain representative embodiments, the base station 114 a and theWTRUs 102 a, 102 b, 102 c may implement radio technologies such as IEEE802.16 (e.g., worldwide interoperability for microwave access (WiMAX)),CDMA2000, CDMA2000 1×, CDMA2000 evolution-data optimized (EV-DO),Interim Standard 2000 (IS-2000), Interim Standard 95 (IS-95), InterimStandard 856 (IS-856), global system for mobile communications (GSM),enhanced data rates for GSM evolution (EDGE), and/or GSM/EDGE RAN(GERAN), among others.

The base station 114 b may be a wireless router, HNB, HeNB, and/or AP,for example, and may utilize any suitable RAT for facilitating wirelessconnectivity in a localized area, such as a place of business, a home, avehicle, and/or a campus, among others. In certain representativeembodiments, the base station 114 b and the WTRUs 102 c, 102 d mayimplement a radio technology such as IEEE 802.11 to establish a wirelesslocal area network (WLAN). In certain representative embodiments, thebase station 114 b and the WTRUs 102 c, 102 d may implement a radiotechnology such as IEEE 802.15 to establish a wireless personal areanetwork (WPAN). In certain representative embodiments, the base station114 b and the WTRUs 102 c, 102 d may utilize a cellular-based RAT (e.g.,WCDMA, CDMA2000, GSM, LTE, and/or LTE-A, among others), to establish apicocell or femtocell. As shown in FIG. 1A, the base station 114 b mayhave a direct connection to the Internet 110. Thus, the base station 114b may or may not access the Internet 110 via the core network 106.

The RAN 104 may be in communication with the core network 106, which maybe any type of network configured to provide voice, data, applications,and/or voice, over Internet protocol (VoIP) services, among others, toone or more of the WTRUs 102 a, 102 b, 102 c, 102 d. For example, thecore network 106 may provide call control, billing services, mobilelocation-based services, pre-paid calling, Internet connectivity, and/orvideo distribution, among others, and/or may perform high-level securityfunctions, such as user authentication. Although not shown in FIG. 1A,it is contemplated that the RAN 104 and/or the core network 106 may bein direct or indirect communication with other RANs that may employ thesame RAT or a different RAT as those of the RAN 104. For example, inaddition to being connected to the RAN 104, which may be utilizing anE-UTRA radio technology, the core network 106 may be in communicationwith another RAN (not shown) employing a GSM radio technology.

The core network 106 may serve as a gateway for the WTRUs 102 a, 102 b,102 c, 102 d to access the PSTN 108, the Internet 110, and/or othernetworks 112, among others. The PSTN 108 may include circuit-switchedtelephone networks that may provide plain old telephone service (POTS).The Internet 110 may include a global system of interconnected computernetworks and devices that use common communication protocols, such asthe transmission control protocol (TCP), user datagram protocol (UDP)and/or the Internet protocol (IP) in the TCP/IP suite, among others. Theother networks 112 may include wired or wireless communications networksowned and/or operated by one or more service providers. For example, theother networks 112 may include another core network connected to one ormore RANs, which may employ the same RAT or a different RAT as those ofthe RAN 104.

Some or all of the WTRUs 102 a, 102 b, 102 c, 102 d in the communicationsystem 100 may include multi-mode capabilities, e.g., the WTRUs 102 a,102 b, 102 c, 102 d may include multiple transceivers for communicatingwith different wireless networks over different wireless links. Forexample, the WTRU 102 c shown in FIG. 1A may be configured tocommunicate with the base station 114 a, which may employ acellular-based radio technology, and with the base station 114 b, whichmay employ an IEEE 802 radio technology (e.g., a WiFi radio technology).

FIG. 1B is a diagram illustrating a representative wirelesstransmit/receive unit (WTRU) that may be used within the communicationsystem of FIG. 1A.

Referring to FIG. 1B, the WTRU 102 may include a processor 118, atransceiver 120, a transmit/receive element, (e.g., an antenna), 122, aspeaker/microphone 124, a keypad 126, a display/touchpad 128, anon-removable memory 130, a removable memory 132, a power source 134, aglobal positioning system (GPS) chipset 136, and/or peripherals 138,among others. It is contemplated that the WTRU 102 may include anysub-combination of the foregoing elements while remaining consistentwith various disclosed embodiments.

The processor 118 may be a general purpose processor, a special purposeprocessor, a conventional processor, a digital signal processor (DSP), amicroprocessor, one or more microprocessors in association with a DSPcore, a controller, a microcontroller, an application specificintegrated circuit (ASIC), a field programmable gate array (FPGA)circuit, an integrated circuit (IC), and/or a state machine, amongothers. The processor 118 may perform signal coding, data processing,power control, input/output processing, and/or any other functionalitythat enables the WTRU 102 to operate in a wireless environment. Theprocessor 118 may be coupled to the transceiver 120, which may becoupled to the transmit/receive element 122. Although FIG. 1B depictsthe processor 118 and the transceiver 120, as separate components, theprocessor 118 and the transceiver 120 may be integrated together in anelectronic package or chip.

The transmit/receive element 122 may be configured to transmit signalsto, or receive signals from, a base station (e.g., the base station 114a) over an air interface 116. For example, in certain representativeembodiments, the transmit/receive element 122 may be an antennaconfigured to transmit and/or receive RF signals. In certainrepresentative embodiments, the transmit/receive element 122 may be anemitter/detector configured to transmit and/or receive IR, UV, orvisible light signals, for example. In certain representativeembodiments, the transmit/receive element 122 may be configured totransmit and receive both RF and light signals. The transmit/receiveelement 122 may be configured to transmit and/or receive any combinationof wireless signals.

Although the transmit/receive element 122 is depicted, as a singleelement, the WTRU 102 may include any number of transmit/receiveelements 122. The WTRU 102 may employ, for example, MIMO technology. Incertain representative embodiments, the WTRU 102 may include two or moretransmit/receive elements 122, (e.g., multiple antennas) fortransmitting and/or receiving wireless signals over the air interface116.

The transceiver 120 may be configured to modulate the signals that areto be transmitted by the transmit/receive element 122 and/or todemodulate the signals that are received by the transmit/receive element122. The WTRU 102 may have multi-mode capabilities such that thetransceiver 120 may include multiple transceivers for enabling the WTRU102 to communicate via multiple RATs, such as UTRA and IEEE 802.11(e.g., a WiFi radio technology), for example.

The processor 118 of the WTRU 102 may be coupled to, and may receiveuser input data from, the speaker/microphone 124, the keypad 126, and/orthe display/touchpad 128 (e.g., a liquid crystal display (LCD) displayunit and/or organic light-emitting diode (OLED) display unit), amongothers. The processor 118 may also output user data to thespeaker/microphone 124, the keypad 126, and/or the display/touchpad 128,among others. The processor 118 may access information from, and maystore data in, any type of suitable memory, such as the non-removablememory 130 and/or the removable memory 132. The non-removable memory 130may include random-access memory (RAM), read-only memory (ROM), a harddisk, and/or any other type of memory storage device, among others. Theremovable memory 132 may include a subscriber identity module (SIM)card, a memory stick, and/or a secure digital (SD) memory card, amongothers. In certain representative embodiments, the memory may benon-transitory memory.

In certain representative embodiments, the processor 118 may accessinformation from, and store data in, memory that is not physicallylocated on the WTRU 102, such as on a server or a home computer (notshown).

The processor 118 may receive power from the power source 134, and maybe configured to distribute and/or to control the power to the othercomponents in the WTRU 102. The power source 134 may be any suitabledevice for powering the WTRU 102. For example, the power source 134 mayinclude one or more dry cell batteries (e.g., nickel-cadmium (NiCd),nickel-zinc (NiZn), nickel metal hydride (NiMH), and/or lithium-ion(Li-ion), among others), solar cells, and/or fuel cells, among others.

The processor 118 may be coupled to the GPS chipset 136, which may beconfigured to provide location information (e.g., longitude andlatitude) regarding the current location of the WTRU 102. In additionto, or in lieu of, the information from the GPS chipset 136, the WTRU102 may receive location information over the air interface 116 from abase station (e.g., base stations 114 a, and/or 114 b) and/or maydetermine its location based on the timing of the signals being receivedfrom two or more nearby base stations. The WTRU 102 may acquire locationinformation by way of any suitable location-determination method whileremaining consistent with various disclosed embodiments.

The processor 118 may be coupled to other peripherals 138, which mayinclude one or more software and/or hardware modules that may provideadditional features, functionality, and/or wired or wirelessconnectivity. For example, the peripherals 138 may include anaccelerometer, an e-compass, a satellite transceiver, a digital camera(for photographs or video), a universal serial bus (USB) port, avibration device, a television transceiver, a hands free headset, aBluetooth® module, a frequency modulated (FM) radio unit, a digitalmusic player, a media player, a video game player module, and/or anInternet browser, among others.

FIG. 1C is a diagram illustrating a representative radio access networkand a representative core network that may be used within thecommunication system of FIG. 1A. The RAN 104 may employ an E-UTRA radiotechnology to communicate with the WTRUs 102 a, 102 b, 102 c over theair interface 116. The RAN 104 may also be in communication with thecore network 106. The RAN 104 may include eNBs 140 a, 140 b, 140 c,although the RAN 104 may include any number of eNBs while remainingconsistent with various embodiments. The eNBs 140 a, 140 b, 140 c mayeach include one or more transceivers for communicating with the WTRUs102 a, 102 b, 102 c over the air interface 116. In certainrepresentative embodiments, the eNBs 140 a, 140 b, 140 c may implementMIMO technology. The eNB 140 a, for example, may use multiple antennasto transmit wireless signals to, and/or receive wireless signals from,the WTRU 102 a.

Each of the eNBs 140 a, 140 b, 140 c may be associated with a particularcell (not shown) and may be configured to handle radio resourcemanagement decisions, handover decisions, and/or scheduling of users inthe UL and/or DL, among others. As shown in FIG. 1C, the eNBs 140 a, 140b, 140 c may communicate with one another over an X2 interface.

The core network 106 shown in FIG. 1C may include a mobility managemententity (MME) 142, a serving gateway 144, and/or a packet data network(PDN) gateway 146, among others. Although each of the foregoing elementsare depicted as part of the core network 106, it is contemplated thatany of these elements may be owned and/or operated by an entity otherthan the core network operator.

The MME 142 may be connected to each of the eNBs 140 a, 140 b, 140 c inthe RAN 104 via an S1 interface and may serve as a control node. Forexample, the MME 142 may be responsible for authenticating users of theWTRUs 102 a, 102 b, 102 c, bearer activation/deactivation, and/orselecting a particular serving gateway during an initial attach of theWTRUs 102 a, 102 b, 102 c, among others. The MME 142 may also provide acontrol plane function for switching between the RAN 104 and other RANs(not shown) that employ other radio technologies, such as GSM or WCDMA.

The serving gateway 144 may be connected to each of the eNBs 140 a, 140b, 140 c in the RAN 104 via the S1 interface. The serving gateway 144may generally route and forward user data packets to/from the WTRUs 102a, 102 b, 102 c. The serving gateway 144 may perform other functions,such as anchoring user planes during inter-eNB handovers, triggeringpaging when DL data is available for the WTRUs 102 a, 102 b, 102 c,and/or managing and/or storing contexts of the WTRUs 102 a, 102 b, 102c, among others.

The serving gateway 144 may be connected to the PDN gateway 146, whichmay provide the WTRUs 102 a, 102 b, 102 c with access to packet-switchednetworks, such as the Internet 110, to facilitate communications betweenthe WTRUs 102 a, 102 b, 102 c and IP-enabled devices.

The core network 106 may facilitate communications with other networks.For example, the core network 106 may provide the WTRUs 102 a, 102 b,102 c with access to circuit-switched networks, such as the PSTN 108, tofacilitate communications between the WTRUs 102 a, 102 b, 102 c andtraditional land-line communications devices. For example, the corenetwork 106 may include, or may communicate with, an IP gateway, (e.g.,an IP multimedia subsystem (IMS) server), that may serve as an interfacebetween the core network 106 and the PSTN 108. The core network 106 mayprovide the WTRUs 102 a, 102 b, 102 c with access to other networks 112,which may include other wired or wireless networks that are owned and/oroperated by other service providers.

Multi-RAT Carrier Aggregration

By example: (1) HSDPA may simultaneously use DL CCs (e.g., up to 4 DLCCs may be available, and may be increased to up to 8 DL CCs) inconjunction with WCDMA to improve bandwidth usage with frequencydiversity and resource pooling; (2) WCDMA may use multiple-inputmultiple-output (MIMO) in multicarrier DL; and (3) HSUPA maysimultaneously use UL CCs. The transmission time interval (TTI) for HSPAmay be a 2 ms subframe.

For universal terrestrial radio access network (UTRAN), the radioresource control (RRC), packet data convergence protocol (PDCP), radiolink control (RLC), MAC-d and MAC-is sub-layers may be located in anRNC, while MAC-hs, MAC-i and layer 1 (L1) may be located in a Node-B.Security, (e.g., ciphering), segmentation and reassembly services to theMAC, in-order delivery services to the PDCP may be provided by the RLC,and the MAC may ensure ordering between the hybrid automatic repeatrequest (HARQ) processes for the RLC layer.

For LTE, each radio frame (e.g., 10 ms) may include 10 equally sizedsub-frames of 1 ms, (e.g., the TTI for LTE may use a Ims subframe). Byexample, LTE may provide simulaneous transmission and/or reception usingradio resources of a plurality of CCs between an evolved Node-B (eNB)and a WTRU within the same transmission interval. For evolved UTRAN(eUTRAN), there is no radio network controller (RNC), andRRC/PDCP/RLC/MAC layers may be provided (e.g., all located) in the eNB.Security, (e.g., ciphering and integrity protection) and in-orderdelivery services (e.g., at handover) may be provided by a PDCP. The RLCmay provide segmentation, resegmentation and/or reassembly services tothe MAC.

FIG. 2 is a diagram illustrating a representative communication system200 that may be used in the communication system of FIGS. 1A and/or 1C.

Referring to FIG. 2, the communication system 200 may include a SGSN/MMEplatform 210 to support evolved packet core (EPC) and/or General PacketRadio Service (GPRS) core. The SGSN/MME platform 210 may interface via aGb interface (e.g., for control signaling and user data) to a GlobalSystem for Mobile Communications (GSM)/Edge Radio Access Network (GERAN)220. The GERAN 220 may include, for example a Base Station Controller(BSC) 222 and Base Transceiver Station (BTS) 224.

The SGSN/MME platform 210 may interface (e.g., for control signaling)via a lu up/S12 interface to a UTRAN 230. The UTRAN 320 may include aRNC 232 and a node B 234. A Gateway GPRS Serving Support/SystemArchitecture Evolution (GGSN/SAE) gateway 250 may interface with the RNC232 via a lu/Gn-UP interface (e.g., for user data). The GGSN/SAE gateway250 may interface to a packet data network 260, such as the Internet,via a Gi interface (e.g., for user data) and may interface with theSGSN/MME platform 210 (e.g., for control signaling and user data). TheSGN/MME platform 210 may interface via a S1-C interface (e.g., forcontrol signaling) to the LTE network 240. The LTE network 240 mayinclude an eNB 242. The GGSN/SAE gateway 250 may interface via an S1-Uinterface (e.g., for user data) to the eNB 242.

The packet data network architecture of FIG. 2 may support numerous RATsincluding, for example, the GERAN RAT 220, the UTRAN RAT 230 and/or theeUTRAN/LTE RAT 240. Operators may deploy LTE using the same sites as thesites used for WCDMA (e.g., legacy WCDMA) deployments, for example, toreduce planning and deployment costs and the reuse deployment sites.Operators may or may not deploy both WCDMA/HSPA and LTE in the samecoverage areas as a data enhancement overlay. Multi-mode WTRUs 102,(e.g., which may support WCDMA/HSPA access and/or LTE access and/or WiFiaccess), may be widely deployed.

HSPA with MIMO may offer DL peak data rates of, for example, 42 Mbps,and multicarrier HSPA may increase the peak rate by providing up to fourDL CCs. LTE may include up to 100 Mbps in the single carrier DL and LTE,for example, with intra-RAT carrier aggregation may increase the peakrate by combining transmission resources of up to 5 CCs for example, toreduce the cost of offering higher data rates to maximize usage ofdeployed RATs, (e.g., through load balancing), or to maximize usage ofradio components in the WTRU 102, (e.g., using a dual-band receiver).

Operators may use inter-RAT carrier aggregation to enable reservation offrequency band, (e.g., for HeNB deployment) and combining HSPA resourceswith LTE resources may ensure service continuity, (e.g., either forcircuit switched (CS) voice and/or for services using LTE data rates).

Component Carrier (CC) generally refers to a frequency on which a WTRU102 operates. For example, the WTRU 102 may receive transmissions on aDL CC. The DL CC may include a plurality of DL physical channels. Asanother example, the WTRU 102 may perform transmissions on an UL CC. TheUL CC may include a plurality of UL physical channels.

For LTE, the DL physical channels may include, for example, a physicalcontrol format indicator channel (PCFICH), a physical HARQ indicatorchannel (PHICH), a physical data control channel (PDCCH), a physicalmulticast channel (PMCH) and/or a physical data shared channel (PDSCH),among others. On the PCFICH, the WTRU 102 may receive control dataindicating size of the control region of the DL CC. On the PHICH, theWTRU 102 may receive control data indicating HARQ positiveacknowledgement (ACK)/negative acknowledgement (NACK) feedback for aprevious UL transmission. On the PDCCH, the WTRU 102 may receive DLcontrol information (DCI) messages used to schedule DL and UL resources.On the PDSCH, the WTRU 102 may receive user and/or control data.

For LTE, the UL physical channels may include, for example, a physicalUL control channel (PUCCH) and/or a physical UL shared channel (PUSCH),among others. On the PUSCH, the WTRU 102 may transmit user and/orcontrol data. On the PUCCH, and/or the PUSCH, the WTRU 102 may transmitUL control information (such as a channel quality indicator(CQI)/precoding matrix indicator (PMI)/rank indicator (RI) and/orscheduling request (SR)) and/or hybrid automatic repeat request (HARQ)ACK/NACK feedback. On a UL CC, the WTRU 102 may be allocated dedicatedresources for transmission of a sounding reference signal (SRS).

For example, for HSDPA, a shared channel (e.g., a high speed DL sharedchannel (HS-DSCH)) may be used for DL transmission. The HS-DSCH may be atransport channel on which the WTRU 102 may receive user data and/orcontrol signaling from logical channels, such as a dedicated transportchannel (DTCH), a dedicated control channel (DCCH), a common controlchannel (CCCH), and/or a broadcast control channel (BCCH), among others.The WTRU 102 may receive the HS-DSCH on the high speed DL shared channel(HS-PDSCH). The WTRU 102 may receive DL control signaling for schedulingof the HS-PDSCH, (e.g., a transport format including channelizationcode, modulation scheme and transport block size), and/or other types ofcontrol signaling (e.g., discontinuous reception (DRX)/discontinuoustransmission (DTX) activation/deactivation and/oractivation/deactivation commands for additional HSPA cells on thehigh-speed shared control channel (HS-SCCH). The WTRU 102 may transmitUL feedback control information related to HS-PDSCH transmissions and/orrelated to HS-SCCH orders. The UL feedback may include HARQ feedback,CQI and/or precoding control information (PCI) (e.g., if the WTRU 102 isconfigured for MIMO operation) and may be sent on the high-speeddedicated physical control channel (HS-DPCCH) with one for eachconfigured HS-DSCH. Power control commands may be received by the WTRU102 on the DPCH or on the fractional DPCH (hereafter F-DPCH). There maynot be a soft-handover for HS-SCCH and/or HS-DPSCH.

For HSUPA, fast scheduling and fast HARQ for soft combining may use theenhanced dedicated channel (E-DCH). Soft handover may be used for HSUPA.The E-DCH may be mapped on the dedicated physical data channel(E-DPDCH). Each radio link may include zero, one or more E-DPDCHs. TheWTRU 102 may transmit control information associated with the E-DCH onthe E-DCH dedicated physical control channel (E-DPCCH). Each radio linkmay include one E-DPCCH. The dedicated physical DL channels used for ULtransmissions may include the F-DPCH, the E-DCH relative grant channel(E-RGCH), the E-DCH absolute grant channel (E-AGCH) and/or the E-DCHhybrid ARQ indicator channel (E-HICH), among others. The WTRU 102 mayreceive power control commands on the DPCH and/or on the F-DPCH. TheWTRU 102 may receive UL relative grants from the serving and non-servingradio links, over the associated E-RGCH configured by higher layersignaling for each serving and non-serving radio link. The WTRU 102 mayreceive absolute grants for E-DCH from the serving E-DCH cell on theE-AGCH configured by higher layer signaling. The WTRU 102 may receiveHARQ ACK/NACK (A/N) feedback on the E-DCH HARQ Indication Channel(E-HICH).

A cell may include a DL CC which may be linked to a UL CC based on thesystem information (SI) received by the WTRU 102 either broadcasted onthe DL CC and/or using dedicated configuration signaling from thenetwork. For example, when broadcasted on the DL CC, the WTRU 102 mayreceive the UL frequency and bandwidth of the linked UL CC as part ofthe SI element (IE) (e.g., when in RRC_IDLE for LTE, or when inidle/CELL forward access channel (FACH) for WCDMA, e.g., when the WTRU102 does not yet have a radio resource connection to the network). For aWiFi access, a cell may correspond to one or more channel(s) where achannel may correspond to a specific frequency in a frequency band ofthe concerned WiFi technology.

Primary Cell (PCell) generally refers to a cell operating on a primaryor anchor frequency in which the WTRU 102 may perform the initial accessto the system 200, (e.g., in which: (1) the WTRU 102 may perform theinitial connection establishment procedure; (2) the WTRU 102 mayinitiate the connection re-establishment procedure; and/or (3) the cellhad been indicated as the primary cell in the handover procedure, amongothers). The PCell may correspond to a frequency indicated as part ofthe radio resource connection configuration procedure. Certain functionsmay be supported (e.g., only supported) on the PCell. For example, theUL CC of the PCell may correspond to the CC whose physical UL controlchannel resources are configured to carry HARQ feedback (e.g., all HARQACK/NACK feedback) for the WTRU 102 (e.g., a particular WTRU).

For example, in LTE, the WTRU 102 may use the PCell to derive theparameters for the security functions and for upper layer SI such asnon-access stratum (NAS) mobility information. Other functions that maybe supported only on the PCell DL include SI acquisition and changemonitoring procedures on the broadcast channel (BCCH), and paging. InWCDMA, the Primary Serving Cell may be similar to the PCell of LTE.

Secondary Cell (SCell) generally refers to the cell operating on asecondary or supplemental frequency which may be configured after (e.g.,when) a radio resource control connection is established and which mayprovide additional radio resources. SI (e.g., relevant for operation inthe concerned SCell) may be provided using dedicated signaling when theSCell is added to the configuration of the WTRU 102.

Although the parameters for the security functions and for the upperlayer SI may have different values than those broadcasted on the DL ofthe concerned SCell using the SI signaling, the information is referredto as SI of the concerned SCell independent of the method used by theWTRU 102 to acquire this information.

PCell DL and PCell UL generally correspond to the DL CC and the UL CC ofthe PCell, respectively, and SCell DL and SCell UL generally correspondsto the DL CC and the UL CC (if configured) of the SCell, respectively.

Serving cell generally refers to a primary cell (e.g., a PCell) or asecondary cell (e.g., a SCell). For example, for a WTRU 102 that is notconfigured with any SCell or that does not enable operation on multipleCCs, (e.g., via carrier aggregation), one serving cell (e.g., only oneserving cell) may be included (e.g., the PCell). For a WTRU 102 that isconfigured with at least one SCell, the serving cell may include a setof one or more cells corresponding to the PCell and the configuredSCells (e.g., all of the configured SCells).

When the WTRU 102 is configured with at least one SCell, one PCell DLand one PCell UL may be configured and, for each configured SCell, theremay be one SCell DL and one SCell UL (e.g., if configured).

Multi-mode WTRU 102 generally refers to any mobile terminal enabling aplurality of RATs such as any combination of GSM, WCDMA, HSPA, HSDPA,HSUPA and LTE, IEEE 802.11b/g/n, IEEE 802.11y, IEEE 802.16a/h/j/n andIEEE 802.20, cdma2000 lx and/or cdma2000 EV-DO, among others.

Primary RAT (PRAT) and anchor RAT (ARAT) generally refer to a radioaccess technology (e.g., network technology) for which at least oneserving cell is configured as the PCell from which at least one of thefollowing functions, procedures and/or operations may be enabled: (1) anRRC connection (e.g., established and connected using the PCell, forexample, via a single RRC contention); and/or (2) security parameters(e.g., derived using the PCell via a security context, for example, asingle context). In certain representative embodiments, UL resources maybe used to transmit UCI on the serving cell (e.g., only on the servingcell) of a first RAT; and/or at least one serving cell of a first RATmay be used to transmit configured UL resources (e.g., a portion or allof the configured UL resources). In certain representative embodiments,the PRAT and/or the ARAT may be referred to as a serving cell RAT.

Secondary or supplemental RAT (SRAT) and/or non-anchor RAT (NARAT)generally refers to a RAT for which none of the configured serving cellsis the PRAT of the WTRU's configuration.

Multi-RAT operation generally refers to any multi-mode WTRU 102simultaneously configured for operation with at least one CC of a firstRAT, (e.g., a DL CC or a UL CC of one or more cells), and with at leastone CC of a second RAT (e.g., of the same or a different type), (e.g., aDL CC or a UL CC of one or more other cells). The operation on thedifferent CC may occur simultaneously, or near-simultaneously in time.The operation according to different RATs may be sequential, includingon the same CC.

In certain representative embodiments, the multi-mode WTRU 102 may beenabled to provide simultaneous or near-simultaneous operation on CCs ofa plurality of RATs. The multi-mode WTRU 102 may be configured tooperate on one or more serving cells where at least one serving cellcorrespond to a first RAT and at least a second serving cell correspondsto a second RAT. The multi-mode WTRU 102 may perform DL and/or ULtransmissions using different RATs, and may operate on differentfrequencies.

In certain representative embodiments, CC aggregation may be appliedacross multiple RATs. For example, representative procedures may bebased on the CC aggregation by a WTRU 102 of at least one CC on radiofrequencies used for an LTE deployment together with at least one CC onradio frequencies used for a HSPA deployment. The procedures may providean RRC connection (e.g., a single RRC connection) that may be used tocontrol radio resources of a plurality of RATs supported concurrently bythe WTRU 102. For example, representative procedures may be based on theCC aggregation by a WTRU 102 of at least one CC on radio frequenciesused for an HSPA deployment together with at least one CC on radiofrequencies used for a LTE deployment. The representative procedures mayprovide an RRC connection (e.g., a single RRC connection) that may beused to control radio resources of a plurality of RATs supportedconcurrently by the WTRU 102. For example, representative procedures maybe based on the CC aggregation by a WTRU 102 of at least one CC on radiofrequencies used for a 3GPP deployment (e.g., LTE and/or HSPA) togetherwith at least one channel within at least one radio frequency band usedfor a WiFi network. The procedures may provide an RRC connection (e.g.,a single RRC connection) of a 3GPP technology that may be used toconfigure and/or control radio resources of both a 3GPP RAT and a WiFiRAT supported concurrently by the WTRU 102. Such a representative CCaggregation procedure may be referred to as multi-RAT CA.

In certain representative embodiments, another representative proceduremay include the WTRU 102 concurrently using one RRC connection for eachrespective RAT of the plurality of RATs that are applicable to orassociated with different sets of at least one CC. The different sets ofat least one CC may operate on different frequencies (e.g., respectivefrequencies). For example, the representative procedures may be based onthe WTRU 102 using radio resources on at least one frequency where LTEis deployed and simultaneously or near simultaneously using other radioresources on at least one frequency used for a HSPA deployment. Therepresentative procedures may provide a plurality of radio resourceconnections, (e.g., one for each RAT concurrently used by the WTRU 102),that may control the respective radio resources. Such procedures inwhich a WTRU 102 concurrently operates (CO) using a plurality of RRCconnections may be referred to as multi-RAT CO.

In certain representative embodiments, the WTRU 102 may transmit usingdifferent RATs in different time intervals (e.g., only in different timeintervals, as a form of time division operation on a TTI basis) on thesame or different frequencies or frequency bands.

In certain representative embodiments, the CC aggregation may use atleast one frequency on a CC on which the WTRU 102 may operate accordingto a first RAT, and at least one frequency on a second CC on which theWTRU 102 may operate according to a second RAT.

For example, the WTRU 102 using multi-RAT CA procedures and using LTEand WCDMA/HSPA RATs may be configured based on:

-   -   (1) an initial access using LTE and additional resources using        WCDMA/HSPA such that the WTRU 102 may initiate access using LTE        to establish a single RRC connection to the LTE system; and/or    -   (The network may reconfigure the WTRU 102 with additional        resources for accessing the WCDMA/HSPA system using multi-RAT        operation (e.g., the serving cells configured for LTE operation        may correspond to a primary RAT and serving cells configured for        WCDMA/HSPA operation may correspond to a secondary RAT); and/or    -   (2) an initial access using WCDMA/HSPA and additional resources        using LTE such that the WTRU 102 may initiate access using        WCDMA/HSPA to establish a single RRC connection to the        WCDMA/HSPA system.    -   (The network may then reconfigure the WTRU 102 with additional        resources for accessing the LTE system using multi-RAT        operation. In other words, the serving cells configured for        WCDMA/HSPA operation may correspond to the primary RAT, while        the serving cells configured for LTE operation may correspond to        the secondary RAT.)

Although multi-RAT CA procedures are described using LTE and WCDMA/HSPARATs, it is contemplated that the procedures may be applicable to anycombination of any number of other RATs such as GSM, WCDMA, HSPA, HSDPA,HSUPA, LTE, 802.11b/g/n, IEEE 802.11y, 802.16a/h/j/n, 802.20 in IEEE,cdma2000 1× and/or cdma2000 EV-DO, among others.

For example, the WTRU 102 using multi-RAT CA procedures and using a 3GPP(e.g., HSPA and/or LTE) and WiFi RATs may be configured based on aninitial access using a 3GPP RAT and additional resources using WiFi suchthat the WTRU 102 may initiate access using a 3GPP RAT to establish asingle RRC connection to the 3GPP system. The network may reconfigurethe WTRU 102 with additional parameters for accessing the WiFi systemusing multi-RAT operation (e.g., the serving cells configured for afirst 3GPP RAT operation may correspond to a primary RAT and servingcells configured for WiFi operation may correspond to a secondary RAT).The parameters configured by the 3GPP RAT RRC connection and foraccessing the WiFi system may be at least one of a frequency band of theWiFi network, a specific frequency (e.g., a channel) for the WiFinetwork, an operation mode for the WiFi network (e.g., Direct-SequenceSpread Spectrum (DSSS) or Orthogonal Frequency Division Multiplexing(OFDM)), an identity of the WiFi network (e.g. a Serving Set IDentifier(SSID)), an identity of the WiFi access point (e.g. a Basic SSID (BSSID)and/or a MAC identity), a set of one or more security parametersincluding at least one of a security protocol, an encryption algorithmand/or a security key. The configuration may include an indication toturn on (e.g. activate) the WiFi transceiver in the WTRU. The type ofsecurity protocol may be one of: a Wired Equivalent Privacy (WPA), Wi-FiProtected Access (WPA) or WPA II (WPA2), among others. The type ofencryption algorithm may be one of a Temporal Key Integrity Protocol(TKIP), or a Pre-Share Key mode (PSK), among others. The security keymay be a string of hexadecimal digits, and/or a bitstring, among others,and may correspond to information (e.g., a passphrase) from which a WiFidevice may further derive the encryption key using a known keyderivation function.

The multi-mode WTRU 102 may be configured for multi-RAT operation suchthat different combinations of DLs and/or ULs (e.g., if any) of CCs ofthe secondary RAT may be used. For example, the following multi-RATaggregation scenarios may be used:

(1) the WTRU 102 may be configured with at least one DL CC for thesecondary RAT (e.g., only DL CCs);

(2) the WTRU 102 may be configured with at least one DL CC and at leastone UL CC for the secondary RAT; and/or

(3) the WTRU 102 may be configured with at least one UL CC for thesecondary RAT (e.g., only UL CCs).

The WTRU 102 may operate on a plurality of CCs with at least twodifferent CC associated with respectively different RATs. Certainrepresentative procedures may be applicable when the first and thesecond CCs operate on the same frequency such that the WTRU 102 mayoperate according to a first RAT during a first period of time andaccording to a second RAT during a second period of time, (e.g., in atime-division manner).

The WTRU 102 may operate with a single RRC instance including a singlestate machine for the control plane. The RRC procedure may be performedon the radio resources of a first CC of the first RAT, and may be usedto configure radio resources of at least one CC of the second RAT.

In certain representative embodiments, the multi-mode WTRU 102 may beconfigured using a radio resource connection procedure of the first RAT,performed on the radio resources of the serving cell of the first RAT,where the WTRU 102 is provided with a configuration for using additionalradio resources of at least one CC of the second RAT. The WTRU 102 mayoperate with a single state machine for the RRC connection, which statesand state transitions may correspond at least in part to those of thefirst RAT. The WTRU 102 may maintain the single RRC connection to thenetwork, (e.g., on the primary serving cell (e.g., PCell) of the firstRAT). The WTRU 102 may maintain the single RRC state machine usingstates and corresponding transitions of the first RAT. The WTRU 102 maymaintain and may perform a single NAS connection on the first RAT (e.g.,the PCell). For example, the NAS procedures, registrations, and/or NASmobility information may be performed on the first RAT (e.g., only thefirst RAT)). The WTRU 102 may determine the security parameters,algorithms and/or other information used to perform the securityprocedures via the first RAT.

In certain representative embodiments, the CC(s) of the second RATserving the WTRU 102 may be a DL CC or a UL CC.

In certain representative embodiments, the first RAT (e.g., of thePCell) serving the WTRU 102 may operate as an LTE RAT (e.g., may beconfigured for LTE operations) and the concerned DL CC or CCs of thesecond RAT (e.g., of the SCell) serving the WTRU 102 may operate as anHSDPA RAT (e.g., may be configured for HSDPA operation). In certainrepresentative embodiments, the first RAT (e.g., of the PCell) servingthe WTRU 102 may operate as an LTE RAT (e.g., may be configured for LTEoperations) and the concerned DL CC or CCs of the second RAT (e.g., ofthe SCell) serving the WTRU 102 may operate as an HSUPA RAT (e.g., beconfigured for HSUPA operation).

In certain representative embodiments, the first RAT (e.g., of thePCell) may operate according to a WCDMA/HSPA RAT and the concerned DL CCor CCs of the second RAT (e.g., of the SCell) serving the WTRU 102 mayoperate as an LTE RAT (e.g., may be configured for LTE operations).

In certain representative embodiments, the first RAT (e.g., of thePCell) may operate according to a 3GPP RAT (e.g. a WCDMA/HSPA RAT, or aLTE RAT) and the concerned cell(s) of the second RAT (e.g., of theSCell) serving the WTRU 102 may operate as a WiFi RAT (e.g., may beconfigured for WiFi operations).

In certain representative embodiments, the concerned CCs of the secondRAT may include at least one DL CC and one UL CC, and may correspond tothe serving cell.

In certain representative embodiments, the first RAT may operateaccording to the LTE RAT and the serving cell configured for the secondRAT may be configured for HSPA operation.

In certain representative embodiments, the first RAT may operateaccording to the WCDMA/HSPA RAT and the serving cell configured for thesecond RAT may be configured for LTE operation.

In certain representative embodiments, the representative proceduresdescribed herein may be applied to a pair of the concerned CCs in whichone DL CC and one UL CC may be associated to form the serving cell ofthe WTRU 102, (e.g., a secondary serving cell, or a SCell).

In certain representative embodiments, the multi-mode WTRU 102 maysupport two or more of: (1) LTE; (2) WCDMA; (3) HSDPA; (4) HSUPA and/or(5) WiFi.

As one example, an LTE RRC reconfiguration procedure (e.g., withoutmobility control information), may be performed on radio resources ofthe serving cell (e.g., the PCell) on which the WTRU 102 is served andthe serving cell may operate according to LTE RAT operations. The LTERRC reconfiguration may include a radio resource configuration for atleast one concerned CC of the second RAT on which the WTRU 102 mayoperate according to: WCDMA RAT operations, HSDPA RAT operations and/orHSUPA RAT operations. The WTRU 102 may maintain a single RRC statemachine using the LTE states and corresponding transitions.

As another example, the multi-mode WTRU 102 may support LTE and WCDMAand/or HSDPA and/or HSUPA. A WCDMA/HSPA RRC reconfiguration procedure,(e.g., without mobility control information) may be performed on radioresources of the serving cell on which the WTRU 102 is served and theserving cell may operate according to WCDMA/HSPA RAT operations. TheWCDMA/HSPA reconfiguration may include radio resource configuration forat least one concerned CC of the second RAT on which the WTRU 102operates according to the LTE RAT operations. The WTRU 102 may maintaina single RRC state machine using the WCDMA/HSPA states and correspondingtransitions.

The WTRU 102 may operate with one RRC instance and/or one RRC statemachine for the control plane for each RAT for which at least oneserving cell is configured. A subset or all of the RRC proceduresspecific to each RAT may be performed on the radio resources of thecorresponding RAT independent of the RRC states of the other RAT orRATS. Parameters obtained using higher layer procedures, (e.g., NASprocedures) performed over the RRC connection of the first RAT may beused to configure corresponding parameters of the RRC connection of thesecond RAT. For example, these parameters may include a packet dataprotocol (PDP) context and a security context. In certain representativeembodiments, parameters obtained using higher layer procedures, (e.g.NAS procedures) performed over the RRC connection of the first RAT maybe used to configure parameters for the second RAT. For example, theseparameters for accessing a WiFi system may include a frequency band, aspecific frequency (e.g. a channel), an operation mode (e.g., DSSS orOFDM, among others), an identity of the WiFi network (e.g., SSID), anidentity of the WiFi access point (e.g., BSSID), a set of one or moresecurity parameters including at least one of a security protocol, anencryption algorithm and/or a security key. The configuration mayinclude an indication to turn on (e.g. activate) the WiFi transceiver inthe WTRU 102.

In certain representative embodiments, the multi-mode WTRU 102 may beconfigured for multi-RAT (or multi-CO) operation such that the WTRU 102may operate with one state machine for each RRC connection (e.g., havingstates and state transitions that may correspond at least in part tothose of the corresponding RAT).

In certain representative embodiments, the multi-mode WTRU 102 maysupport LTE and WCDMA (and/or HSDPA and/or HSUPA), and may be configuredfor multi-RAT operation with LTE as the primary RAT and WCDMA/HSPA asthe secondary RAT. In certain representative embodiments, the multi-modeWTRU 102 may support LTE and WCDMA and/or HSDPA and/or HSUPA, and may beconfigured for multi-RAT operation with WCDMA/HSPA, as the primary RAT,and LTE, as the secondary RAT.

The WTRU 102 may operate with at least a common part of the user plane,(e.g., different possible combinations for the PDCP, RLC, and MAClayers), where a first part corresponds to the user plane of the firstRAT and, if any, a second part corresponds to the user plane of thesecond RAT.

In certain representative embodiments, the multi-mode WTRU 102configured for multi-RAT operation may access multiple RATs under thecoordination/supervision of the network, (e.g., based on radio resourceconfiguration and/or control signaling for scheduling). The WTRU 102 mayfirst establish a control path (e.g., a single control path and/or asingle RRC connection), to the network, (e.g., to the eNB 240 in case ofLTE RRC). The network may setup a single user data path to/from the corenetwork 106, (e.g., the IP gateway, the SGSN, the GGSN, access gatewayand the like), while it may at any time transmit/receive the user dataover a radio channel of any of the configured CCs for any RATs. From anetwork connectivity perspective, the WTRU 102 may be a single IP devicewith a single control (RRC connection) path and a single securitycontext. The branching of the data path may be implemented for the caseof a multi-mode WTRU operating with a multi-RAT configuration.

The following representative procedures describe how a WTRU 102 mayhandle branching of the data path (e.g., which may carry user planedata) and/or control plane data, when the multi-mode WTRU 102 isconfigured for multi-RAT operation. In a first representative procedure,branching may be performed under an IP layer and above a PDCP layer. Forexample, a separate PDCP/RLC/MAC chain (e.g., one chain) per set ofconfigured CCs that belong to the same RAT may be implemented. Therepresentative procedure may use one security context, (e.g., securityparameters and keys), for each set of CCs, and each set of CCs mayinclude their own security algorithms. For example, security on an LTEchain may be applied in the LTE PDCP and security for the HSPA chain maybe applied in an RLC layer. Additional network signaling may use a newnetwork interface and may signal between a UTRA RNC (PDCP, RLC) in thenetwork and the LTE eNB 242, (e.g., if LTE is used for the RRCconnection).

In a second representative procedure, the branching may be performedunder the PDCP layer and above the RLC layer. For example, a common PDCPentity may handle the RLC/MAC chain for each set of CCs that belong tothe same RAT. When the WTRU 102 operates with at least one LTE servingcell as the first RAT, and is configured with at least one CC of thesecond RAT that is, for example, WCDMA and/or HSDPA (and/or HSUPA) orWiFi. If the LTE PDCP is used, the WTRU 102 may use a single securitycontext/algorithms and, if configured, may use a single headercompression context. Additional network signaling may use a new networkinterface and may signal between a UTRA RNC (PDCP, RLC) in the networkand the LTE eNB 242, (e.g., if LTE is used for the RRC connection).

In a third representative procedure, the branching may be performedunder the RLC layer and above a respective MAC entity of each set of CCbelonging to the same RAT. For example, a common PDCP entity and acommon RLC entity may handle at least one MAC entity for each set of CCsthat belong to the same RAT.

When the WTRU 102 operates with at least one LTE serving cell as a firstRAT, and is configured with at least one CC of the second RAT that is,for example, WCDMA and/or HSDPA (and/or HSUPA). If the LTE PDCP is used,the WTRU 102 may use a single security context/algorithms, and, ifconfigured, may use a single header compression context, and LTE RLC maybe used for segmentation/resegmentation and reassembly.

In a fourth representative procedure, the branching may be performed inthe MAC entity above a respective HARQ entity of each set of CCsbelonging to the same RAT. For example, individual scheduling andresource management entities may be used that manage the resources andthat determine the transport block size of each RAT. The transport blockcreated on each RAT may include a common MAC header format that may betransmitted on one or more other RATS (e.g., different RATs) over therespective CCs.

The WTRU operation may be applied based on associations between CCsacross RATs. The operations described herein may be applied tocombinations of CCs belonging to different RATs using some form ofassociation. The association between multiple configured CCs for a givenWTRU 102 may be based on, for example, at least one of the followingprocedures (e.g., which may be applicable to all of the embodiments whenapplied to CCs of different RATs). For example, a set of configured CCsmay use: (1) “dedicated-linking,” (e.g., based on a configurationsignaled to the WTRU 102 using dedicated signaling); (2)“scheduling-linking,” (e.g., based on the CC being addressable forscheduling from the control channel of a first CC used for thescheduling of a second CC); and/or (3) “HARQ feedback-linking,” (e.g.,based on the HARQ feedback relationship either for DL and/or for ULfeedback, and/or the use of other types of control signaling between thebase station and the WTRU across CCs operating using different RATs).The configured CCs may be based on “scheduling-linking,” (e.g., based onassociations such as those derived from cross-carrier scheduling on acontrol channel of the first CC for transmissions for the second CC of adifferent RAT).

The radio resource reconfiguration message may include a configurationor a reconfiguration of the multi-RAT such that the WTRU 102 may add,modify and/or remove at least part of the radio configuration foroperation on the secondary RAT and/or the configuration for at least oneof the serving cell of the secondary RAT.

A handover command may include a configuration of the multi-RAT suchthat the WTRU 102 may resume multi-RAT operation at handover to anothereNB 242 for both the first RAT and the second RAT.

In certain representative embodiments, a multi-mode WTRU 102, forexample, may monitor radio link quality, may detect radio link problems,may declare failure for a CC and/or may take other actions, when it isconfigured for multi-RAT operation.

In a first representative embodiment, when the WTRU 102 detectsinsufficient radio quality, (e.g., if a radio link failure (RLF) isdetermined) on a CC of the second RAT, it may take certain actions andmay notify the network using radio resources of a CC of the first RAT.

In a second representative embodiment, the multi-mode WTRU 102 may beconfigured for multi-RAT operation and may determine that the radioquality is insufficient (e.g., if the RLF is determined) of at least oneCC of a second RAT and it may notify the network using radio resourcesof a CC of a first RAT.

In certain representative embodiments, the notification may be a L3message (e.g., RRC) and/or a L2 message, (e.g., MAC CE).

In certain representative embodiments, the WTRU 102 may determine thatthe radio quality is insufficient, (e.g., a RLF) for a CC of the secondRAT that is used as a path loss reference for UL transmissions.

In certain representative embodiments, the first RAT may be an LTE RATand the second RAT may be a WCDMA RAT and/or HSDPA RAT (and/or HSUPARAT).

If the WTRU 102 is configured with RAT-specific measurements, when ameasurement configuration event triggers a measurement report, the WTRU102 may either transmit (1) a report for all configured and availablemeasurements for all configured RATs or (2) the WTRU 102 may transmit(e.g., only transmit) measurement reports for the RAT that triggered themeasurements report. Which report is transmitted by the WTRU 102 may beconfigured by higher layers.

In certain representative embodiments, a multi-mode WTRU 102 may performa random access procedure, when it is configured for multi-RAToperation. Control signaling for requesting the WTRU 102 to perform therandom access procedure in the second RAT may be received on a CC of thefirst RAT.

In certain representative embodiments, the multi-mode WTRU 102 may beconfigured for multi-RAT operation and may initiate the random accessprocedure using resources of a CC of the second RAT based on controlsignaling received in a CC of the first RAT.

In certain representative embodiments, the first RAT may be an LTE RATand the second RAT may be a WCDMA RAT and/or a HSDPA RAT (and/or a HSUPARAT).

In certain representative embodiments, the first RAT may be a WCDMA RATand/or a HSDPA RAT (and/or a HSUPA RAT) and the second RAT may be a LTERAT.

In certain representative embodiments, the first RAT may be a 3GPP RAT(e.g. WCDMA RAT and/or a HSDPA RAT and/or a HSUPA RAT, or a LTE RAT) andthe second RAT may be a WiFi RAT.

In certain representative embodiments, the control signaling may be anorder from the network to perform random access received on the PDCCH ofa CC of the first RAT.

In certain representative embodiments, a random access response receivedon a CC of the first RAT may include a grant that is applicable for atransmission on a CC of the second RAT. For example, the WTRU 102 mayreceive dedicated parameters of the second RAT, such as a dedicatedrandom access preamble, in a random access (RA) response. Controlsignaling for scheduling of a CC of the second RAT may be received on aCC of the first RAT.

In certain representative embodiments, a multi-mode WTRU 102 may beconfigured for multi-RAT operation and may determine whether or notradio resources are allocated to the WTRU 102 for a transmission on atleast one CC of the second RAT based on control signaling received inthe first RAT.

In certain representative embodiments, the control signaling, (e.g., oneor more grants and/or assignments) may be received on the physical datatransport channel of the first RAT, (e.g., on a resource block of thePDSCH for LTE).

In certain representative embodiments, the first RAT may be an LTE RATand the second RAT may be a WCDMA RAT and/or a HSDPA RAT (and/or a HSUPARAT) and the control signaling for scheduling may be received on the LTEPDCCH. The scheduling may be received on the PDCCH of a CC configured byRRC for cross-carrier scheduling of the concerned CC of the second RAT.

In certain representative embodiments, the Downlink Control Information(DCI) may be used to schedule transmissions on radio resources of thesecond RAT and may be in a DCI format that may be specific to the typeof RAT that is being cross-carrier scheduled. The DCI format may bescrambled using a specific Radio Network Temporary Identifier (RNTI),which may indicate the identity of the CC of the second RAT. The DCIformat may be received in a WTRU-specific search space of the PDCCH of aCC of the first RAT. The search space may be specific to at least one CCof the second RAT. The search space may not overlap with any othersearch space and the successful decoding of the DCI format in the searchspace may implicitly determines the identity of the CC of the second RATto which the DCI is applicable (e.g., associated with).

In certain representative embodiments, the WTRU 102 may not decode anycontrol signaling for the scheduling of a CC of the second RAT, when theCC is deactivated and/or if the CC may not be scheduled based on a powersaving algorithm applicable to at least the CC. Control signaling forActivation/Deactivation of a CC of the second RAT may be received on aCC of the first RAT.

In certain representative embodiments, the multi-mode WTRU 102 may beconfigured for multi-RAT operation and may determine theactivation/deactivation state of at least one CC of the second RAT basedon control signaling received in the first RAT.

In certain representative embodiments, the control signaling may bereceived using: (1) L1 signaling, (e.g., via a LTE PDCCH or HSPA HS-SCCHorder); (2) L2 signaling (e.g., via a MAC CE); (3) L3 signaling (e.g.,via a RRC service data unit (SDU) which may be used as part of theconfiguration message that adds at least one CC of the second RAT to theWTRU's configuration).

In certain representative embodiments, the first RAT may be an LTE RATand the second RAT may be a WCDMA RAT and/or a HSDPA RAT (and/or a HSUPARAT) and the control signaling for activation/deactivation may becarried using a MAC CE. The MAC CE may include a bitmap where at leastone bit may be used for each configured CC (or serving cell) of thesecond RAT and the bit may represent the activation state of anindividual the CC. The mapping of a bit in the bitmap may be configuredusing dedicated RRC signaling when adding the CC, either based on anexplicit serving cell identity based on: (1) an order of the servingcell identity of the configured secondary serving cell or serving cellsfor the WTRU 102; (2) the configuration order of the serving cells; (3)and/or any other similar procedure.

In certain representative embodiments, the first RAT may be HSPA, (e.g.,which may include both UL HSUPA and DL HSDPA), and the second RAT may bean LTE RAT and the control signaling for activation/deactivation may becarried using a HS-SCCH order. In a first example, the multi-cellHS-SCCH order type may be used to control the activation/deactivationstatus of the serving cells across both RATs. The order of the servingcells (e.g., controlled by the HS-SCCH order) may be set according to anexplicit network configuration such that each serving cell from bothRATs may be assigned a serving cell ID. In certain representativeembodiments, the order of the serving cells may be determined accordingto a predetermined rule, for example, the cells of the first RAT may bethe first ones in order of the serving cell IDs or in order of theconfiguration and the serving cells of the secondary cells may be thenext ones according to the order the serving cell IDs or according to aconfiguration order.

In certain representative embodiments, a new HS-SCCH order type may beused to control the activation/deactivation of the cells in thesecondary RAT. The mapping of the order bits and the combination of theorder bits to the serving cells may follow similar rules to themulti-cell HS-SCCH order type.

In certain representative embodiments, the multi-mode WTRU 102configured for multi-RAT operation may determine theactivation/deactivation state of at least one CC of the second RAT suchthat: (1) activation control may be performed based on control signalingreceived in the first RAT and/or (2) deactivation control may beperformed based on control signaling received in the first RAT.

In certain representative embodiments, the multi-mode WTRU 102configured for multi-RAT operation may determine theactivation/deactivation state of at least one CC of the second RAT suchthat deactivation control may be performed based on a deactivation timerthat may be applicable either to: (1) each configured CCs individually;(2) a subset of configured CCs (e.g., based on configured CCs of a sameRAT type); and/or (3) all configured CCs.

In certain representative embodiments, the multi-mode WTRU 102configured for multi-RAT operation may determine whether or not it may:(1) decode the control signaling for scheduling, (e.g., PDCCH forPDSCH/PUSCH scheduling for LTE); and/or (2) transmit on configuredperiodic resource, if any, of a configured UL CC, (e.g., periodicCQI/PMI/RI reporting on PUCCH in LTE, or PCI reporting in HSPA).

In certain representative embodiments, procedures may allow DRXoperation across two RATs. Representative procedures to perform DRX inboth RATs may include the use of different parameters, operations,restrictions, and/or timing for DRX in the aggregated RATs.

In a first representative embodiment, both RATs may use a common DRXstatus, (e.g., long/short DRX or active/not active status) andconfiguration. For example, one common DRX configuration may be providedon a first RAT and may be used across both RATs. To achieve timealignment across the two RATs and to ensure the correct reception of thescheduling channel on the second RAT, the DRX parameters provided forthe first RAT may be multiples of the TTI length of the other RAT (e.g.,if the TTI length of the first RAT is greater than the TTI length of thesecond RAT). For example, when an LTE RAT is the first RAT and an HSPARAT is the second RAT, the DRX parameters, such as cycles, on durationsand/or offsets may be a multiple of 2 ms or equivalently multiples oftwo LTE sub-frames.

In certain representative embodiments, triggers that may cause the WTRU102 to transition to continuous or discontinuous reception on the firstRAT, may cause the WTRU 102 to transition to continuous reception on thesecond RAT. The initiation of a DRX or the on duration may correspond tothe subframe boundary of both RATs.

In certain representative embodiments, the DRX may be independent acrossboth RATs. For example, the DRX configuration and orders may beindependently provided for each RAT and may allow realization ofscenarios in which different services are transmitted over differentRATs, while optimizing battery saving opportunities, (e.g., voice onHSPA and web browsing on LTE).

In certain representative embodiments, the configuration, (e.g., cyclesand/or on durations, among others), may be common across the RATs, whilethe status and triggers to go in and out of DRX may be different acrossthe RATs.

In certain representative embodiments, control signaling received in afirst RAT may be considered or used in the power saving algorithm of thesecond RAT such that scheduling activity in the first RAT may trigger,for example, a change in a DRX state in the second RAT. For example,control signaling received in the first RAT for cross-carrier schedulingof data on resources of the second RAT may be used (e.g., considered) ascontrol signaling received in the second RAT for the power savingalgorithm of the second RAT.

In certain representative procedures, a multi-mode WTRU 102 may beconfigured for multi-RAT operation and may determine whether or not itmay use resources of the first RAT or of the second RAT to request ULtransmission resources. For example, for the WTRU 102 that is configuredwith UL resources (e.g., only UL resources) for the first RAT, (e.g., ina multi-RAT CA scenario), the WTRU 102 may use the scheduling requestprocedure of the first RAT to request UL resources. In otherrepresentative procedures, for the WTRU 102 that is configured withadditional UL resources (e.g., for the second RAT, the WTRU 102 maydetermine which scheduling request (SR) procedure to use based on, forexample, which resources to use in which CC. The determination of the SRprocedure may be a function of at least one of:

(1) the next occurrence in time of a SR transmission occasion, acrossconfigured UL resources (e.g., all configured UL resources) for the SRon the CCs (e.g., any CCs), for example, to minimize latency;

(When an SR is triggered, the WTRU 102 may select the next available ULresource for the SR transmission (e.g., only considering activated ULcarriers). In certain representative embodiments, the WTRU 102 may use adeactivated carrier configured with such resource, and may implicitlyactivate at least the CC.)

(2) the type of data that triggered the SR;

(For example, if the data bearer for which data has triggered the SR isconfigured such that the data may be transmitted on radio resources ofthe second RAT, then, if configured and/or available, the WTRU 102 mayuse the SR resources of the second RAT to signal for UL radio resourceson the second RAT);

(3) whether or not the WTRU 102 may perform other UL transmissions inthe same subframe on any other configured and active CC, and the type oftransmissions;

(For example, if a WTRU 102 performs an UL transmission in a CC of thefirst RAT, it may perform the SR transmission on the resources of thesecond RAT instead of the resources of the first RAT, if available.)

The resource or resources to use in which CC may be a function of anassociation between a type of data and a specific RAT. The type of datamay be a function of one or more of: (1) the transport service, (e.g.,TCP, UDP, and/or RTP, among others); (2), the QoS requirements orthresholds (e.g., QCI, maximum delay, and/or maximum packet loss rate,among others); (3) the associated logical channel and/or logical channelgroup; (4) the type of radio bearer, (e.g., signaling radio bearer (SRB)or data radio bearer (DRB)); (5) the operator's policy for the type ofdata or the type of application, (e.g., voice, background traffic, besteffort, and/or real-time, among others) (e.g., configured by RRC in asemi-static manner).

Which resource to use in which CC may be a function of the estimatedradio link quality (e.g., a function of the latest measurements (such asreference signal received quality (RSRQ) and/or reference signalreceived power (RSRP)), or a carrier on which the WTRU 102 is notexperiencing insufficient radio quality, (e.g., radio link failure(RLF)).

The resource or resources to use in which CC may be a function of thetype of RAT. For example, when the SR is triggered, the WTRU 102 mayselect (e.g., may always select) a CC of the first RAT. For example, theWTRU 102 may select (e.g., always select) the PCell of the first RAT.

In certain representative embodiments, the above procedures may consider(e.g., use) available (e.g., only available) dedicated resourcesconfigured for the SR. When the WTRU 102 does not have configureddedicated resources for the SR in at least one of the RATs, it may use(e.g. consider) random access resources (e.g., random access (RA)-SR)and may use similar procedures as those described above for the RACHresource or resources. The WTRU 102 may also use both the dedicatedresources and the random access resources of configured (e.g., allconfigured) CCs, when using the above procedures.

The WTRU 102 may report one or more RAT-specific buffer status reports(BSRs), in the case of at least one SRB map and/or DRB map to one ormore CCs of a single RAT.

In certain representative embodiments, a multi-mode WTRU 102 may beconfigured for multi-RAT operation and may determine one or moretransport blocks to use for transmission of different types of dataand/or control signaling, when the multi-mode WTRU 102 is configured formulti-RAT operation.

Which transport block or blocks to use may be a function of: (1) thetype of service (e.g., VoIP service, best-effort service, TCP service,gaming service, and/or browsing service, among others); (2) the type ofradio bearer (e.g., SRB and/or DRB, among others); (3) the QoS channelindication (QCI); (4) associated SRB/DRB priority (or lack of theassociated SRB/DRB priority); (5) associated logical channel(LCH)/logical channel group (LCG); (6) an explicit indication that thedata to or data from a given radio bearer may be transmitted using atransport block of a specific CC; and/or (7) the RAT type. The CC may bedetermined based on at least one of: (1) the type of RAT, (e.g., LTEand/or HSPA, among others); (2) an identity corresponding to the CC,(e.g., SCell ID); (3) the size of the transport block; (4) an explicitindication in the control signaling for scheduling, (e.g., a flag in aLTE DCI received on the PDCCH when cross-carrier scheduling is used);and/or (5) the type of transport channel associated to the transportblock, among others.

The WTRU 102 may transmit data on particular UL radio resources as afunction of the type of data, (control signaling/control plane/userplane), and the type of allocated radio resources.

In certain representative embodiments, a multi-mode WTRU 102 configuredfor multi-RAT operation may determine data to be transmitted on aparticular UL resource based on the data's association to a specificradio bearer, (e.g., SRB, DRB, LCH, and/or LCG, among others), and/orbased on the type of RAT of the CC of the concerned transport block.

In certain representative embodiments, the WTRU 102 may determine thatdata associated with a specific SRB may be transmitted (.e.g., mayalways be transmitted) in the UL using the resources of the first RAT.

In certain representative embodiments, the WTRU 102 may determine thatdata associated with a specific DRB (an/or a specific LCH/LCG) may betransmitted on a transport block of a CC that belongs to either thefirst RAT or to the second RAT based on a configuration of the WTRU 102,for example, when the WTRU 102 may be explicitly configured by thenetwork using RRC to transmit data from the DRB using radio resources ofthe second RAT (e.g., for data of a VoIP service).

In certain representative embodiments, the WTRU 102 may determine that aMAC CE for reporting (e.g., buffer status, power headroom and/or othersimilar UL scheduling control information) may be transmitted on atransport block of a CC that belongs to either the first RAT or to thesecond RAT based on a configuration of the WTRU 102, e.g., when theradio resources of the first RAT may be used (e.g., always used) fortransmission of BSR, and/or power headroom report (PHR), among others.

In certain representative embodiments, the first RAT may be LTE and thesecond RAT may be WCDMA and/or HSDPA (and/or HSUPA). The transmission ofUL Control Information (UCI) corresponding to at least one CC of thesecond RAT may be transmitted on UL transmissions of a CC of the firstRAT.

The UCI may include: (1) HARQ A/N feedback for DL transmissions; (2) thechannel quality indication (CQI); (3) precoding matrix information(PMI); (4) a scheduling request (SR); (5) RI; and/or (6) the PCI, amongothers. Typically, HARQ A/N feedback may be transmitted to inform thenetwork about the status of one or more DL transmissions, (e.g., atransport block, or a codeword), for a given TTI and CQI/PMI/RI, whichmay be typically reported based on a periodic configuration and/or anexplicit request from the network. The SR may be transmitted to informthe network that there may be UL data to transmit.

For the WTRU 102 operating in multiple RATs, a UL control channel forHARQ ACK/NACK and/or for CQI/PMI/RI reports may not be available for thesecond RAT (e.g., in the case where no (and/or insufficient) ULresources are configured, no (and/or insufficient) UL resources areallocated, no (and/or insufficient) UL resources are activated, and/orfor any other reasons which may prevent the WTRU 102 from performingtransmissions on the control channel (e.g., insufficient availabletransmission power, invalid timing alignment, invalid path lossreference, and/or a RLF detected, among others). In such cases, onerepresentative procedure may enable the WTRU 102 to transmit at leastpart of the UCI corresponding to the second RAT on UL resources of thefirst RAT. In certain representative procedures, the multi-mode WTRU 102configured for multi-RAT operation may transmit (e.g., always transmit)at least part of the UCI corresponding to the second RAT on UL resourcesof the first RAT.

In certain representative embodiments, the multi-mode WTRU 102configured for multi-RAT operation may also be configured to use the ULresources of the first RAT to transmit at least parts of the UCIcorresponding to the second RAT. In certain representative embodiments,the first RAT may be an LTE RAT and the second RAT may be a WCDMA RATand/or an HSDPA RAT and/or HSUPA RAT. In certain representativeembodiments, the first RAT may be a 3GPP RAT (e.g., LTE RAT, or WCDMARAT and/or an HSDPA RAT and/or HSUPA RAT) and the second RAT may be aWiFi RAT.

In certain representative embodiments, the UL resources of the first RATused may be in a PUCCH format, (e.g., a LTE PUCCH Format 3).

In certain representative embodiments, a set of UL resources of thefirst RAT may be used for channel selection on the resources, (e.g., LTEchannel selection using any of PUCCH Format 1a/1b/2a/2b, or PUCCH Format3).

In certain representative embodiments, the UL resources of the first RATused may consist of or include a PUSCH transmission, for example, in thePCell of the WTRU's LTE configuration, if the WTRU 102 is configured forcarrier aggregation (CA) for the LTE RAT.

In certain representative embodiments, at least parts of the UCI may betransmitted on a first UL resource of the first RAT, and another partmay be transmitted on a second UL resource of the first RAT. Forexample, the WTRU 102 may transmit HARQ ACK/NACK bits on a PUCCHresource and CQI/PMI/RI bits may be transmitted on a PUSCH transmission(either on the PCell, or on a SCell).

The following representative procedures enable the WTRU 102 to performpower headroom reporting, when the multi-mode WTRU 102 is configured formulti-RAT operation. For the multi-mode WTRU 102 configured formulti-RAT operation, when calculating the available power headroom for aset of CC of each RAT type, the WTRU 102 may use the total transmissionpower across sets (e.g., all sets) of CCs. In certain representativeprocedures, the transmission power may be based on activated (e.g., onlyactivated) UL carriers in each set.

In a first representative procedure, when the WTRU 102 receives a radioresource configuration that adds at least one CC of the second RAT, theWTRU 102 may trigger a PHR for each configured serving cell that haveconfigured UL resources, for CCs of the first RAT and the CCs of thesecond RAT (e.g., the PHR may be triggered for a portion or all of theUL resources, for example for all serving cells or only activatedserving cells).

In a second representative procedure, when the WTRU 102 receives controlsignaling that activates at least one CC of the second RAT, the WTRU 102may trigger a PHR for each configured serving cell that have configuredUL resources, for CCs of the first RAT and CCs of the second RAT (e.g.,the WTRU 102 may trigger a portion or all of the UL resources, forexample for all serving cells or only activated serving cells).

In a third representative procedure, the multi-mode WTRU 102 configuredfor multi-RAT operation may trigger a PHR for all CCs configured for theWTRU 102 and any RAT type (e.g., for activated (e.g., only activated)serving cells with configured UL resources, if the WTRU 102 receives aradio resource configuration that adds at least one CC of the secondRAT. The WTRU 102 may receive activation/deactivation control signalingthat may activate at least one CC of the second RAT and/or maydeactivate at least one CC of the second RAT. In certain representativeprocedures, the first RAT may be LTE and the second RAT may be WCDMAand/or HSDPA (and/or HSUPA).

In certain representative embodiments, handling of different subframetiming for scheduling-related operations across carriers of differentRATs may be implemented.

When the transmission time interval (TTI) of HSPA physical channels is 2ms, (e.g., about 2 ms for HS-PDSCH) and the subframe duration of LTEphysical channels, (e.g., PDSCH) may be 1 ms (e.g., about 1 ms), thefollowing representative embodiments may describe timing relationshipsbetween the reception of control signaling on a DL physical channel ofthe first RAT for a transmission on a physical channel of the second RATand for cross-carrier scheduling, activation/deactivation, and/or anyother procedure affected by the control signal, (e.g., DRX timers,and/or Time Alignment Timers, among others).

When the control signal is received on the first RAT in a subframe N1corresponding to the subframe timing of the first RAT, the correspondingsubframe N2 corresponding to the subframe timing of the second RAT andused for deriving the timing for performing the corresponding operationon a physical channel of the second RAT may be determined according toany of the following subframe N2: (1) during which or at the start ofwhich subframe N1 may start; (2) which may be the first subframe atwhich a starting boundary occurs during subframe N1; (3) which may bethe first subframe at which a starting boundary occurs during which orat the end of which subframe N1 ends; (4) which may be the firstsubframe at which a starting boundary occurs after the end of subframeN1. The determination using subframe N2 may be responsive to the firstRAT being HSPA (e.g., with a 2 ms TTI) and the control signaling beingreceived in subframe N1, (e.g., the HS-SCCH).

When the above timing is used and when scheduling of a HSPAtransmission, (e.g., HS-PDSCH), for a given serving cell is performed ona LTE control channel, (e.g., PDCCH), the reception timing of the LTEcontrol signal, (e.g., PDCCH), may be used to derive the receptiontiming for the HSPA transmission, (e.g., HS-PDSCH), on the correspondingserving cell.

When the above timing is used and when scheduling of the PDSCHtransmission for a given serving cell is performed on a HSPA controlchannel, the reception timing of the HSPA control signal may be used toderive the PDSCH reception timing on the corresponding serving cell.

If the first RAT is LTE (e.g., with a 1 ms TTI), multi-RAT aggregationin the MAC may be performed.

In certain representative embodiments, procedures to configure themulti-mode WTRU 102 using a single radio resource connection, (e.g.,RRC), on the first RAT, (e.g., LTE or HSPA), with at least one DL CC ofthe second RAT, (e.g., HSPA or LTE respectively) may be implemented.

Although LTE and HSPA are described as representative RATs for carrieraggregation, it is contemplated that other RATs, e.g., disclosed aboveand, for example, a WiFi RAT, may be equally applicable.

Although various representative procedures are described herein in thecontext of DL, it is contemplated that they are equally applicable tothe UL.

In certain representative embodiment, procedures may allow aggregationof the first RAT and the second RAT such that the data plane and thecontrol plane may be aggregated using a common PDCP/RLC of the primaryRAT and the data may be separated at the MAC layer between the MAC of aprimary RAT and the MAC of a secondary RAT. In this representativescenario, the primary RAT may establish the control plane and the userplane, the user plane and control plane protocol stack may comprise aPDCP, a RLC, a RRC, and a NAS of the primary RAT and a MAC and PHY ofboth primary and secondary RATs.

In certain representative embodiments, the logical channels, (e.g., theDTCH, DCCH, and/or CCCH), of the primary RAT may be mapped to the LTEDL-SCH and/or to HSPA DL HS-DSCH transport channels, which may then bemapped to LTE PDSCH and HSPA HS-DPSCH physical channels, respectively.

FIG. 3 is a diagram illustrating a mapping 300 of representative DLlogical channels to transport channels, where LTE is the primary RAT andboth user plane and control plane data or logical channels may be mappedto LTE DL-SCH or HSPA HS-DSCH.

The DL logical channels 305 may include:

(1) a Paging Control Channel (PCCH) 315 configured as a DL channel thatmay transfer paging information and SI change notifications (e.g., thechannel may be used for paging when the network does not know thelocation cell of the WTRU 102);

(2) a Broadcast Control Channel (BCCH) 320 configured as a DL channelfor broadcasting system control information;

(3) a Common Control Channel (CCCH) 325 configured as a channel fortransmitting control information between the WTRU 102 and the network(e.g., the channel may be used for the WTRUs having no RRC connectionwith the network);

(4) a Dedicated Control Channel (DCCH) 330 configured as apoint-to-point bi-directional channel that may transmit dedicatedcontrol information between the WTRU 102 and the network and may be usedby the WTRUs 102 having an RRC connection;

(5) a Dedicated Traffic Channel (DTCH) 335 configured as apoint-to-point channel, dedicated to one WTRU 102, for the transfer ofuser information (e.g., the DTCH 335 can exist in both UL and DL);

(6) a Multicast Control Channel (MCCH) 340 configured as apoint-to-multipoint DL channel that may be used for transmitting MBMScontrol information from the network to the WTRU 102, for one or severalMulticast Traffic Channel s (MTCHs) 345 (e.g., the MCCH 340 may be used(e.g., may only be used) by WTRUs 102 that may receive MBMS; and/or

(7) a MTCH 345 configured for the transmission of multicast data.

The DL transport channels 310 may include: (1) a Paging Channel (PCH)350 which maps to the PCCH 315 and may support UE discontinuousreception (DRX) to enable WTRU 102 power saving (e.g., the DRX cycle maybe indicated by the network to the WTRU 102) and may be broadcast;

(2) a Broadcast Channel (BCH) 355 which may map to the BCCH 320;

(3) a High-Speed Downlink Shared Channel (HS-DSCH) 360, which may map tothe DCCH 330 and/or the DTCH 335 and may enable at least 3 physicallayer channels (not shown) (e.g. a High Speed-Shared Control Channel(HS-SCCH) an Uplink High Speed-Dedicated Physical Control Channel(HS-DPCCH) and a High Speed-Physical Downlink Shared Channel (HS-PDSCH)such that the HS-SCCH may inform the user that data is to be sent on theHS-DSCH (e.g., 2 slots ahead), the HS-DPCCH may carry acknowledgmentinformation and the current CQI of the user. This value may be used bythe base station (e.g., base stations 114 and/or 234) to calculate howmuch data to send to the user devices on the next transmission and theHS-PDSCH may be the channel mapped to the HS-DSCH 360 transport channelthat may carry actual user data);

(4) a Downlink Shared Channel (DL-SCH) 365 which may be mapped to theBCCH 320, the CCCH 325, the DCCH 330 and/or the DTCH 335 (this transportchannel may be the main channel for DL data transfer.

(5) a Multicast Channel (MCH) 370 may be mapped to the MCCH 340 and/orthe MTCH 345, may be broadcast in the entire coverage area of the cell,and may be used to transmit MCCH information to set up multicasttransmissions.

When HSPA is the primary RAT, a mapping similar to that shown in FIG. 3may apply. Even though not shown in FIG. 3, the CCCH logical channel mayalso be mapped to the HS-DSCH 360 transport channel. In certainrepresentative embodiments, the aggregation may be performed for userplane data or logical channels, (e.g., only for DTCH 335), and thecontrol plane logical channels, (DCCH 330 and/or CCCH 325), may bemapped to the primary RAT logical channels. In certain representativeembodiments, the aggregation may be performed for dedicated logicalchannels, (e.g., DCCH 330 and DTCH 335), and common logical channelssuch as the CCCH 325 may be mapped to the primary RAT. In certainrepresentative embodiments, for each logical channel established, anexplicit configuration may be used to indicate whether the configuredlogical channel may be mapped over two RATs, only over the primary RAT,or only over the secondary RAT.

For DL aggregation only, in one example where LTE is the primary RAT,the UTRA DL secondary cells may be limited to the transmission of theHS-SCCH and HS-DPSCH physical channels and may be CPICH for theassociated WTRU 102. For UL aggregation, a number of additional physicalchannels may be configured to allow the proper operation of UTRA UL.

In one example, where HSPA is the primary RAT, for DL aggregation, theE-UTRA secondary cells may include transmission of at least: PDSCH,PDCCH, CRS, CSI-RS, or any signaling used by the WTRU 102 to decode theDL data and perform correct channel estimation.

In one representative scenario, the LTE may be configured, as a primaryRAT. In this representative scenario, one LTE PDCP and one LTE RLCentity may be established per configured bearer, in addition to or inlieu of the LTE NAS and, for example, RRC. The PDCP and RLC may becommon and the data may be scheduled on either the LTE MAC or UMTS MAC.The UMTS MAC, over which the LTE logical channels may be scheduled, maycorrespond to an MAC-ehs entity, and the MAC-ehs entity functionality(e.g., all the MAC-ehs entity functionality) may be maintained or a newMAC entity may be used. For UL multi-RAT aggregation, the UMTS MAC maycorrespond to MAC-i/is or to a new MAC. Procedures are described belowthat may achieve multi-RAT aggregation when LTE is a primary RAT andHSPA is a secondary RAT.

The interaction between the HSPA MAC, LTE MAC and the physical layersmay be similar to the DL, for UL aggregation of HSPA with LTE, as thefirst RAT, the LTE logical channels may be mapped to either UL-SCH or toE-DCH. In this example, data from any RLC logical channel or data fromlogical channels that may be allowed to be transmitted over both RATs,may be multiplexed and mapped over either a HS-DSCH (or E-DCH) transportchannel or DL-DSCH (or UL-PUSCH) transport channels.

For the DL, the LTE WTRU 102 may receive and de-multiplex data for anylogical channel from either a HS-DSCH transport channel or DL-DSCHtransport channels and the corresponding physical channels.

FIG. 4 is a diagram illustrating a representative Layer 2 (L2) structure400.

FIG. 5 is a diagram of a representative MAC-ehs module 500 used in theHSPA MAC 474 of FIG. 4.

Referring to FIG. 4, the L2 structure 400 may be for an eNB sideimplementation such that an eNB scheduler, (e.g., aggregation schedulingand priority handling), in the MAC may determine whether to route thedata to an LTE MAC 464 or an HSPA MAC 474. The LTE MAC 464 and HSPA MAC474 are shown as not including the handling unit 462 for simplicity. TheLTE MAC 464 and HSPA MAC 474, each may include portions of the handlingunit 462. The L2 structure may include a plurality of sublayers, forexample, a Packet Data Convergence Protocol (PDCP) layer 440, an RLClayer 450 and/or an aggregated MAC layer 460, among others, for example,for the DL. As shown in FIG. 4, the PDCP layer 440 may include RobustHeader Compression (ROHC) processing at ROHC entity 442 and securityprocessing at security entity 444 and the data may be provided to theRLC layer 450. The RLC layer 450 may include a segmentation andAutomatic Repeat Request (ARQ) entity 452. For example, the radiobearers 402 may be processed via the PDCP layer 440 and the RLC layer450 to generate logical channels or channel traffic 404, which may beprovided to MAC layer 460.

The MAC layer 460 may provide aggregation, scheduling and priorityhandling of the multiple logical channels 404 via the handling unit 462(e.g., common to and shared by the HSPA and LTE MACs), and multiplexingthe scheduled traffic from the logical channels 404 into DL-SCH dataunits via the LTE MAC 464 or DL HS DSCH data units via the HSPA MAC 474that may be transmitted over the air by the physical layer. The LTE MAC464 may include a LTE scheduler 466, a multiplexer 468 and HybridAutomatic Repeat Request (HARQ) entities 470. The HSPA MAC 474 mayinclude HSPA MAC-ehs 476 and HARQ entities 478.

The HSPA MAC 474 may correspond to a MAC-ehs entity, which may includeat least one MAC-ehs module 500, as shown in FIG. 5. The MAC-ehs module500 may include a scheduling/priority handling unit 510, a priorityqueue distribution 520, a plurality of priority queues 530, a pluralityof segmentation units 540 and a priority queue multiplexer (PQMUX) 550.The MAC ehs module 500 may provide the data to the HARQ entity 478. Forexample, the scheduling/priority handling unit 510 which may provide orperform the scheduling/priority handling functions may manage HS-DSCHresources between HARQ entities 478 and data flows according to theirpriority class. The PQMUX 550 may determine the number of octets to beincluded in a MAC-ehs PDU from each priority queue based on thescheduling decision and available transport format and resourcecombination (TFRC) for this function, the segmentation unit 540 mayperform segmentation of MAC-ehs service data units (SDUs) and the TFRCselection unit 560 may select an appropriate transport format andresource for the data to be transmitted on the HS-DSCH. The MAC-ehsentity may also provide associated UL and/or DL signaling.

Certain representative procedures may allow reception of data overmultiple RATs on the WTRU 102 side. If LTE is the primary RAT, inaddition to the LTE protocol stack, (e.g., physical layer, MAC, RLC,PDCP, RRC), at least the following HSPA configuration may be provided tothe WTRU 102: (1) a MAC-ehs entity and the applicable configurationparameters or the HS-DSCH physical channel resources and configurationparameters. The WTRU 102 may be configured to start receiving HS-SCCHand HS-DPSCH on the secondary RAT (e.g., the HSPA RAT). The datareceived over the HS-DPSCH may be processed by the MAC-ehs entity (e.g.,the HSPA), the HARQ entity 478 and associated HSPA MAC functionalities,and data received over the DL-DSCH may be processed by the LTE HARQprocesses and de-multiplexed according to the LTE MAC protocol headers.

FIG. 6 is a diagram illustrating a representative implementation of aWTRU MAC architecture 600. FIG. 7 is a diagram of a representativeMAC-ehs module 700 used in the MAC architecture 600.

Referring to FIG. 6, the WTRU MAC architecture 600 may be exchange datawith upper layers 610 and a lower layer 630. The upper layers 610 maycorrespond to the DL logical channels of FIG. 3 and may include MACcontrol. The lower layer 630 may correspond to the DL transport channelsof FIG. 3 and may include an UL-SCH. The MAC layer 620 may include alogical channel prioritization 621 (e.g., for the UL only), amultiplexer/demultplexer 622 (e.g., for LTE only), a demultiplexer 623,a HARQ entity 624, a MAC-ehs entity 625 (e.g., for DL only), randomaccess control 626 and a control 627 for managing or controlling otherfunctions, modules and/or entities of the MAC layer 620. The MAC-ehsentity 625 on the WTRU 102 side may include at least one MAC-ehs, forexample, as shown in FIG. 7.

For example: (1) the PCCH 315 and PCH 350 may be coupled such that dataexchanged via the MAC layer 620 may not be processed (e.g., may be apass-through); (2) the MCCH 340 and the MTCH 345 may be coupled via ademultiplexer 623 to the MCH 370; (3) the BCCH 320 and the BCH 355 maybe coupled such that data exchanged via the MAC layer 620 may not beprocessed (e.g., may be a pass-through); the BCCH 320 may also becoupled via HARQ entity 624 to the DL-SCH 365 (e.g., or UL-SCH) for dataexchange; (4) the CCCH 325, the DCCH 330 and the DTCH 335 may be coupledvia the logical channel prioritization 621 (e.g., for the UL only), themultiplexer/demultplexer 622 (e.g., for LTE only), and the HARQ entity624 to the DL-SCH 365 (e.g., or UL-SCH) for data exchange; and/or (5)the CCCH 325, the DCCH 330 and the DTCH 335 may be coupled via thelogical channel prioritization 621 (e.g., for the UL only), themultiplexer/demultplexer 622 and the MAC-ehs 625 (e.g., for DL only) tothe HS-DSCH 360 for data exchange.

Referring to FIG. 7, the MAC ehs 700 on the WTRU 102 side may include aplurality of LCH-ID demultiplexing entities 710, a plurality ofreassembly entity 720, a plurality of reordering entities 730, areordering queue distribution function 740, a disassembly entity 750 anda plurality of HARQ entities 760. The HARQ entities 760 may handle tasksused for hybrid ARQ including generating ACKs or NACKs. The disassemblyentities 750 may disassemble the MAC-ehs PDUs by removing the MAC-ehsheader and/or padding. The reordering queue distribution function 740may route the received reordering PDUs to reordering queues based on thereceived logical channel identifier. The reordering entities 730 mayorganize received reordering PDUs according to the received TransmissionSequence Number (TSN). Data blocks with consecutive TSNs may bedelivered to reassembly entity upon reception. The reassembly entities720 may reassemble segmented MAC-ehs SDUs and may forward the MAC PDUsto LCH-ID demultiplexing entities 710. The LCH-ID demultiplexingentities 710 may route the MAC-ehs SDUs to one or more logical channelsbased on the received logical channel identifier.

For example, the MAC ehs 625 may include disassembly of the MAC-ehs PDUsaccording to the MAC-ehs protocol headers, the reordering queuedistribution functions, reordering and reassembly functions. The LCH-IDde-multiplexing may be present in the MAC-ehs 625, which may enable theLTE de-multiplexing function 622 in FIG. 6 to be bypassed.

In certain representative embodiments, the LCH-ID de-multiplexingfunctionality may be removed from the MAC-ehs and the LTEde-multiplexing function may be in charge of routing the data to thecorrect logical channel.

The reordering functionality in the MAC (e.g., the MAC-ehs 625) maycause additional delays in the generation of RLC ACK/NACK status reportsand may be due to a timer being present in the RLC protocol to ensurethat packets (e.g., all packets) that may be delayed due to HARQretransmissions have been received prior to transmitting the RLC statusreport.

Since the MAC-ehs 625 may deliver data in order, (e.g., after accountingfor HARQ delays), the timers in the RLC may duplicate (e.g.,unnecessarily duplicate) the delay. In certain representativeembodiments, to reduce such delays, various representative proceduresare described below.

In a first representative procedure, a Ti timer in the MAC-ehs 625 maybe set to one of a plurality of times (e.g., to 10 ms, or to 0 ms). Thismay move the reordering (e.g., all of the reordering) in the RLC.

In a second representative procedure, the RLC may not start a timer ifthe missing sequence numbers are determined to be from the UTRA MAC-ehs.Certain representative procedures may be used to determine over whichinterface the missing data was transmitted based on an interactionbetween the MAC-ehs 625 and the RLC.

If the MAC-ehs 625 is co-located with the LTE RLC, the MAC-ehsfunctionality may be modified, enhanced and/or simplified when LTEaggregation is configured, for example, by taking advantage of theefficiency and optimizations introduced by the upper LTE protocol stack.When the RLC and the MAC-ehs 625 are collocated in the same node, abuffering queue may not be used in the MAC-ehs 625. Since the RLC canperforms re-segmentation of RLC PDUs to ensure that the PDU may fit intothe MAC TB, it is contemplated to remove (or disable) the segmentationfunctionality from the HSPA MAC. To reduce the delays in the RLC due toTSN number and reordering in the WTRU 102, it is contemplated that TSNnumbering and reordering are not each performed by the MAC.

As an example implementation, a LTE aggregated MAC-ehs in a Node B maynot perform the following functionalities: (1) TSN numbering; (2)segmentation; and/or (3) queue distribution. The functionality oroperation of the LTE aggregated MAC-ehs may include one or more of thefollowing: (1) a scheduling/priority handling functionality oroperation, which may manage HS-DSCH resources between HARQ entities anddata flows according to the priority of logical channels;

(2) TFRC selection, which may perform selection of an appropriatetransport format and resource for the data to be transmitted on HS-DSCH;and/or (3) priority handling and multiplexing of data from differentlogical channels. When data is multiplexed and the MAC PDU is createdfor the UTRA HS-DSCH, the eNB may use the UTRA MAC-ehs header format.

An LTE aggregated HSPA MAC in the WTRU 102 may be configured to receiveand de-multiplex MAC PDUs received over the HS-DPSCH. The data may bereceived from the physical layer processes in the HARQ, after which theWTRU 102 may perform de-assembly or de-multiplexing of the HSPA MAC PDUsand may forward them to the correct logical channel, according to theLCH-ID. The enhanced HSPA MAC may not perform reordering queuedistribution, reordering or re-assembly.

In certain representative embodiments, a common MAC header format forthe MAC PDU may be created to be transmitted over the UTRAN. The MACheader format may correspond to the LTE header format such that MAC-PDUcreated may include or may contain a LTE format and may be transmittedover the HS-DPSCH or an E-DPDCH channel. The HARQ transmission and theTFRC (or the E-TFC) selection may be performed according to the UTRANprotocol (e.g., with the MAC header being a LTE MAC header).

On the WTRU 102 side, the functionalities of the MAC-ehs may no longerbe used and MAC-ehs may remain transparent. The WTRU 102 may receivedata over the HS-DPSCH and may use the UTRAN HARQ processcharacteristics. Once the data is properly processed and successfullyreceived, it may be passed to the LTE de-multiplexing entity that mayprocess the data as if it was received over an LTE physical channel. Anexample MAC structure 820 is shown in FIG. 8. The MAC structure 820 issimilar to that of the MAC structure 620 except that themultiplexer/demultplexer 822 may or may not be used for LTE only and anHARQ HSPA entity 825 may be used in lieu of the MAC ehs entity 625 inFIG. 6.

The MAC layer 820 may include a logical channel prioritization 821(e.g., for the UL only), a multiplexer/demultplexer 822, a demultiplexer823, a HARQ entity 824, a HARQ HSPA entity 825, random access control826 and a control 827 for managing or controlling other functions,modules and/or entities of the MAC layer 820.

For example, (1) the PCCH 315 and PCH 350 may be coupled such that dataexchanged via the MAC layer 820 may not be processed (e.g., may be apass-through); (2) the MCCH 340 and the MTCH 345 may be coupled via ademultiplexer 623 to the MCH 370; (3) the BCCH 320 and the BCH 355 maybe coupled such that data exchanged via the MAC layer 820 may not beprocessed (e.g., may be a pass-through); the BCCH 320 may also becoupled via HARQ entity 824 to the DL-SCH 365 (e.g., or UL-SCH) for dataexchange; (4) the CCCH 325, the DCCH 330 and the DTCH 335 may be coupledvia the logical channel prioritization 821 (e.g., for the UL only), themultiplexer/demultplexer 822 (e.g., for LTE only), and the HARQ entity824 to the DL-SCH 365 (e.g., or UL-SCH) for data exchange; and/or (5)the CCCH 325, the DCCH 330 and the DTCH 335 may be coupled via thelogical channel prioritization 821 (e.g., for the UL only), themultiplexer/demultplexer 822 and the HARQ HSPA entity 825 to the HS-DSCH360 for data exchange.

It is understood by one of skill in the art that the concepts describedherein are also applicable to UL E-DCH aggregation, wherein the MAC-i/isis the equivalent UL UTRA MAC entity. For example, similar to the DL,for UL E-DCH, it is contemplated to optimize the functionality of theMAC-i/is, but performing only E-TFC selection and multiplexing of datain the selected MAC PDU. The segmentation and TSN numberingfunctionality may be removed. The LTE MAC PDU header format may also beused for the UTRA UL MAC PDU, similar to the UL.

To allow the aggregation of a plurality of (e.g., two or more) RATs atthe MAC and physical layer, the RRC common control layer may properlycontrol and configure the WTRU 102 to operate with the HSPA MAC-ehs andDL HS-DSPCH. This may be achieved by extending the LTE control plane toincorporate the HSPA MAC and/or physical layer configuration in RRCmessages. The RRC messages may include: (1) RRC ConnectionReconfiguration messages; (2) RRC Connection Reestablishment messages;and/or (3) RRC Connection Setup messages, among others.

The configuration may be included in the message or within an IE in themessage such as IE “RadioResourceConfigDedicated” and/or“PhysicalConfigDedicated” that may include the HSPA physical channelconfiguration parameters. For the DL physical channel configuration, theLTE RRC messages may include a UTRA-DLSecondaryCell-Container. Thecontainer may correspond to a container including IEs encoded accordingan UTRA RRC specification. For the DL, the IE may correspond to IE “DLsecondary cell info”. In certain representative embodiments, IEreception handling from another RAT may be implemented.

If full MAC-ehs functionality is to be configured, anUTRA-MAC-ehsConfig-Container may be used in the above-mentioned RRCmessages. This container may refer to the UTRA IE “Added or reconfiguredMAC-ehs reordering queue”.

The MAC-ehs reordering queues may have an explicit mapping with the LTElogical channels. It is contemplated to use the LTE IE “DRB-to-ADDMod”and/or IE“SRB-to-ADDMod” to include the mapping of the logical channelidentity to one of the MAC-ehs queue identity, (e.g., the MAC-ehs queueID may be added to the IE).

To maintain the LTE IEs (e.g., not modify the LTE IEs), it iscontemplated to include this information in the IE “added orreconfigured MAC-ehs reordering queue”. The new information may include,for each MAC-ehs reordering queue, the LTE logical channel identity thatis mapped to the MAC-ehs queue. Similar to the physical channelconfiguration parameters, specific actions may be implemented to handlethe reception of this IE from another RAT.

It is understood by one of skill in the art that even though thisexample is provided for the MAC and physical channel configuration, theymay be equally applicable to other information, such as UL physicalchannel configuration, RLC, and the like.

The UTRA-container may include all or a portion of the above-mentionedIEs in one message or may use separate containers for each of these IEs.

In certain representative embodiments, procedures may be implemented toallow multi-RAT aggregation in the MAC sub-layer, with HSPA acting asthe primary RAT. The HSPA RLC, PDCP, RRC, and NAS entities may beestablished, and for a multi-RAT configured WTRU 102, two MAC entitiesmay be established (e.g., a HSPA MAC and a LTE MAC) and thecorresponding physical channels. The representative embodiments of FIGS.3-8 described above regarding the mapping of the logical channels andtransport channels are equally applicable for these embodiments.

In certain representative embodiments, independent MAC entities (e.g.,two or more independent MAC entities) may be configured and setup (forexample, an HSPA MAC, (e.g., a MAC-ehs or a MAC-i/is), and a LTE MAC).The data from a logical channel may be sent over a HSPA MAC and/or a LTEMAC. The data may be processed independently from each MAC entity,assembled and transmitted according to functionalities of each RAT.

In certain representative embodiments, the HSPA RLC protocol may rely onthe MAC to perform segmentation of RLC PDUs that may not fit into theselected transport block size (e.g., which the LTE MAC may not support).The RLC PDUs that do not fit into the selected or requested transportblock (TB) may not be included in the MAC PDU, and these RLC PDUs may betransmitted either over the HSPA MAC or in a subsequent TTI.

In certain representative embodiments, the TB size to be transmittedover both RATs may be independently selected by each RAT. The HSPA MACmay assemble and construct the MAC PDU that may be transmitted overeither HSPA or LTE physical channels and HARQ processes. This may allowthe HSPA MAC to perform additional operations such as segmentation ofRLC PDUs and/or TSN numbering per logical channel. The MAC headerapplied to the MAC PDUs may correspond to that of the HSPA MAC headerand the MAC PDU created to be transmitted over LTE may be passed to theLTE HARQ and may be sent over the LTE physical channels. On thereceiving side, the data received over the LTE and HSPA physicalchannels may be processed and combined in the corresponding HARQprocesses of LTE and HSPA, respectively. After a TB is successfullydecoded from any of the RATs, the HARQ process may forward the data tothe HSPA MAC entity that may de-multiplex, reorder, reassemble andforward to the corresponding logical channel.

In certain representative embodiments, the TSN and SI fields may beadded to each PDU created for each logical channel and the created PDUmay be multiplexed and processed by the different MAC entities. As anexample, in the UL (or DL), a MAC-is PDU (or MAC-ehs reordering PDU) maybe forwarded to one of: (1) a MAC-i entity (or MAC-ehs multiplexingfunction); or (2) an LTE MAC entity such that additional MAC headers maybe added and the HSPA MAC PDU or the LTE MAC PDU, respectively, may becreated. On the receiving side, the data received from each RAT may beprocessed and de-multiplexed by the corresponding LTE or HSPA MAC entityand may be forwarded and processed by the HSPA function that may reorderand reassemble the data and route them to the correct logical channel.

In certain representative embodiments, procedures may be implemented forallowing the transmission of UCI pertaining to HSPA signals,(hereinafter referred to as “HSPA UCI”), from at least one carrier overat least one LTE UL physical channel such as the physical UL controlchannel (PUCCH) or the physical UL shared channel (PUSCH). Unlessotherwise specified, the following representative procedures may applyto transmission over any of these channels, which are collectivelyreferred to as the “LTE UL physical channel” (or PUxCH). The PUxCH mayinclude: (1) an HSPA signal, which may generally refer to: (i) atransmission over the HS-SCCH channel and/or the HS-PDSCH (at thephysical layer) and/or (ii) a transmission over the HS-DSCH transportchannel; and/or (2) the HSPA UCI, which may include at least (i)ACK/NACK to DL control information (such as HS-SCCH orders), (ii) HARQACK/NACK, (iii) Channel state information, (iv) Pre-coding Information,and/or (v) Rank Information, among others.

If the transmission time interval (TTI) of the HS-DSCH is (e.g., is 2ms) and the subframe duration of either PUCCH or PUSCH is (e.g., 1 ms),the following representative embodiments may provide timingrelationships between reception of HSPA signals from a DL CC andtransmission of corresponding UCI over an LTE physical channel.

In certain representative embodiments, the HSPA UCI corresponding to aspecific HSPA signal may be transmitted on the PUxCH over a single LTEsubframe (e.g., of 1 ms). Such transmission may occur in subframe N+k,where k is a parameter of either fixed value or a value provided byhigher layers, and N is the reference subframe of the HSPA signal in theLTE subframe numbering. For example, the reference subframe N maycorrespond to at least one of: (1) the subframe during which (or at thestart of which) the HS-SCCH transmission starts; (2) the subframe duringwhich (or at the start of which) the HS-PDSCH transmission starts; or(3) the subframe during which (or at the start of which) the HS-DSCHtransmission starts.

In certain representative embodiments, the HSPA UCI corresponding to aspecific HSPA signal may be transmitted on the PUxCH over two LTEsubframes (e.g., of 1 ms). Such transmission may occur in subframes N+kand N+k+1. It is contemplated that similar timing may be applied to: (1)UL transmission on PUSCH for cross-carrier scheduling used acrossserving cells of different RATs and/or for WTRU 102 operations such asactivation/deactivation of serving cells, among others.

With respect to the selection of a specific PUCCH or PUSCH fortransmission of the HSPA UCI, the following representative proceduresmay be employed including: (1) the HSPA UCI may be transmitted (e.g.,always transmitted) on the PUCCH, (e.g., if (e.g., only if) thepossibility of simultaneous PUCCH and PUSCH transmission is configuredby higher layers; (2) the HSPA UCI may be transmitted over the samesingle physical channel and same UL CC as the LTE UCI, according torules applicable to the selection of physical UL channel for thetransmission of LTE UCI; and/or (3) a first part of the HSPA UCI may betransmitted in a first PUxCH and a second part of the HSPA UCI may betransmitted in a second PUxCH, among others. For instance, the HARQ A/Npart of HSPA UCI may be transmitted on the PUCCH and the CSI part of theHSPA UCI may be transmitted on the PUSCH.

The following representative embodiments may be applicable for thetransmission of HSPA UCI over PUCCH.

The expression “corresponding PDCCH/PDSCH transmission” generally refersto a PDCCH/PDSCH transmission for which the corresponding UCI (e.g.,HARQ A/N) may be transmitted in the concerned subframe. Similarly, theexpression “corresponding HS-SCCH transmission” generally refers to aHS-SCCH transmission for which the corresponding UCI (A/N or HARQ A/N)may be transmitted in the concerned subframe.

The PUCCH resource used to transmit the HSPA UCI and/or the LTE UCI maybe obtained according to at least one of the following proceduresincluding: (1) a PUCCH resource index may be received from thecorresponding HS-SCCH transmission (e.g., if (e.g., only if) nocorresponding PDSCH transmission (or no corresponding PDSCH transmissionfor a secondary LTE serving cell) is received);

(2) the PUCCH resource index may be received from the PDCCH of acorresponding LTE transmission (e.g., if (e.g., only if) a correspondingPDSCH transmission for a secondary LTE serving cell is received); (Incertain representative embodiments, if a corresponding PDSCHtransmission does not exist, the resource index may be obtained from aPDCCH encoded with a format (e.g., specific format) indicating thetransmission of one or more HSPA signals from one or more HSPA DL CCs.)(3) the PUCCH resource index may be provided by higher layers (e.g.,when (e.g., only when) no resource index may be signaled from either aPDCCH or HS-SCCH transmission;

(4) the PUCCH resource to use is the same as the PUCCH resource used inan immediately preceding subframe, (e.g., where the HSPA UCI istransmitted over two subframes (e.g., N+k and N+k+1)).

In certain representative embodiments, procedures may be implemented forallowing the transmission of UCI pertaining to LTE signals (hereinafterreferred to as “LTE UCI”) from at least one carrier over at least oneHSPA UL physical channel such as the HS-DPCCH, the E-DPCCH and/or thededicated physical control channel (DPCCH). Unless otherwise specifiedthe following procedures may apply to transmission over any of thesechannels, which may be collectively referred to as “HSPA UL physicalchannel” (or HS-DPxCH) in the following.

A LTE signal generally refers to a transmission over the PDCCH channeland/or the PDSCH channel (at the physical layer) or a transmission overthe DL-SCH transport channel.

If the transmission time interval (TTI) of the DL-SCH in LTE is (e.g., 1ms), and the subframe duration of a HSPA UL physical channel such as theHS-DPCCH is (e.g., 2 ms), the following representative embodiments maydescribe or identify the timing relationships between reception of LTEsignals from a DL CC and transmission of corresponding UCI over an HSPAUL physical channel including the LTE UCI corresponding to LTE signalsfrom two consecutive LTE subframes (e.g., of 1 ms) that may betransmitted in a single subframe (e.g., 2 ms subframe) of the HS-DPCCH.For example, the LTE UCI transmitted in subframe N (in the HSPA ULsubframe numbering) may correspond to LTE signals that have beentransmitted at the start or during subframe N-k and N-k+1, where k is aparameter of either fixed value or a value provided by higher layers.Similar timing may also be applied to UL transmission on HSPA forcross-carrier scheduling across serving cells of different RATs, and/orWTRU 102 operations such as activation/deactivation of serving cells.

If the capacity of a HS-DPCCH channel for the transmission of LTE UCI,for example, along with the transmission of HSPA UCI is limited,bundling of ACKs or NACKs (A/N) (e.g., AND operation over multiple A/N)corresponding to different transport blocks) may be applied to the LTEUCI prior to inclusion in the HSPA physical channel. For example, thefollowing procedures may be utilized alone or in combination including(1) bundling of A/N of two consecutive LTE subframes; (2) bundling ofA/N in the spatial domain; and/or (3) bundling of A/N corresponding totransport blocks transmitted in a combination of LTE DL CC's and/or HSPADL CC's, among others.

In certain representative embodiments, procedures may be implementedrelating to WTRU 102 concurrently operating on a plurality of CCs usingat least one CC on which the WTRU 102 operates according to a first RATand at least one CC on which the WTRU 102 operates according to a secondRAT.

The WTRU 102 may separately access a plurality of RATs, each using adifferent radio resource connection (e.g., control plane). For example,the WTRU 102 may use a first RAT that may be LTE and a second RAT thatmay be WCDMA and/or HSDPA (and/or HSUPA). The WTRU 102 may establish oneindependent connection to each RAT. From a network connectivityperspective, the WTRU 102 may be viewed as a single device implementingtwo different network interfaces (e.g., IP network interfaces), eachwith its own PDP context, (e.g., IP address), control/user data paths,and security context. RRM, mobility management, scheduling, and/oradmission control may be independent from one another.

FIG. 9 is a flowchart illustrating a representative method 900 formanaging carrier aggregation for a multi-RAT WTRU 102.

Referring to FIG. 9, the representative method 900 may include, at block910, the WTRU 102 receiving over a primary channel associated with a RATof a first type, provisioning information for provisioning asupplementary channel associated with a RAT of a second type. At block920, the WTRU 102 may establish the supplementary channel associatedwith the RAT of the second type based on the received provisioninginformation. At block 930, the WTRU 102 may wirelessly exchange firstdata associated with a communication over the primary channel via theRAT of the first type, while wireless exchanging second data associatedwith the communication over the supplementary channel via the RAT of thesecond type.

Exchanging generally refers to the sending or receiving of data orinformation from one device or entity to another device or entity. Suchan exchange may be one directional (e.g., from a first device to asecond device or may be two directional (e.g., between devices such in aresponse with an acknowledgement).

The terms “while”, “simultaneous”, and “concurrent” generally refer to;(1) a first condition or a first event occurring contemporaneously witha second condition or second event; or (2) that a channel associatedwith the first condition or the first event and a channel associatedwith the second condition or the second event are contemporaneously onor active. For example, these terms may include the direct physicaltransmission of signals at the same time, or interleaved bursts of dataon separate RATs without interrupting the communications of the eitherRAT (e.g., maintaining connectivity of the RAT simultaneously).

In certain representative embodiments, the WTRU may be a UE, or aterminal device for use by an end user, for example, as a cell phone,smart phone, a tablet, and/or netbook, among others. Alternatively, theWTRU may be other components of the radio access network including anetwork access point, a base station, an eNB, and/or a HeNB, amongothers.

In certain representative embodiments, the wirelessly exchanging of thesecond data over the established supplementary channel may include oneof: (1) wirelessly sending the second data over the establishedsupplementary channel; (2) wirelessly receiving the second data over theestablished supplementary channel or (3) wirelessly sending andreceiving different portions of the second data over the establishedsupplementary channel.

In certain representative embodiments, the wirelessly receivingprovisioning information may include receiving via the primary channelassociated with the RAT of the first type control information for theprimary channel and control information for the supplementary channel.

In certain representative embodiments, the first type of RAT may be oneof: (1) a wideband code division multiple access (WCDMA) RAT; (2) a highspeed packet access (HSPA) RAT; (3) a high speed downlink packet access(HSDPA) RAT; (4) a high speed uplink packet access (HSUPA) RAT; or (5) along term evolution (LTE) RAT.

In certain representative embodiments, the second type of RAT may be adifferent one (e.g., different type) of RAT such as: (1) the WCDMA RAT;(2) the HSPA RAT; (3) the HSDPA RAT; (4) the HSUPA RAT; (5) a LTE RAT;(6) a non-cellular RAT; or (7) a WiFi RAT.

In certain representative embodiments, the establishing of thesupplementary channel associated with the RAT of the second type mayinclude determining, from the received provisioning information, one ormore carrier components associated with the RAT of the second type to beprovisioned for wirelessly exchanging the second data over thesupplementary channel; and provisioning the supplementary channel usingthe determined one or more carrier components.

In certain representative embodiments, the representative method mayinclude prior to receiving by the WRTU 102 the provisioning information,establishing the primary channel associated with the RAT of the firsttype.

In certain representative embodiments, the establishing of thesupplementary channel associated with the RAT of the second type mayinclude establishing the supplementary channel using a single radioresource connection to control radio resources of the RATs of the firstand second types.

In certain representative embodiments, the establishing of the singleradio resource connection may include setting up a radio resourcecontrol (RRC) connection.

In certain representative embodiments, the method may include prior toreceiving by the WRTU the provisioning information, establishing theprimary channel associated with the RAT of the first type.

In certain representative embodiments, the establishing of thesupplementary channel associated with the RAT of the second type mayinclude establishing one or more supplementary channels using at leastone respective radio resource connection for each of a plurality ofdifferent RAT types to control radio resources associated with theprimary and one or more supplementary channels supported concurrently bythe WTRU 102.

In certain representative embodiments, the method may includemaintaining the established radio resource connections that may beapplicable to different sets of one or more carrier components.

In certain representative embodiments, the wirelessly exchanging of thefirst data over the primary channel via the RAT of the first type, whilewireless exchanging second data over the supplementary channel via theRAT of the second type may include exchanging respective portions of thefirst and second data of the communication over different ones of theestablished radio resource via the different sets of carrier components.

In certain representative embodiments, the exchanging of the first dataand the second data may include operating the WTRU 102 at a firstfrequency or in a first frequency band for exchange of the first dataand at a second frequency or in a second frequency band that is the sameas or different from the first frequency or the first frequency band.

FIG. 10 is a flowchart illustrating a representative method 1000 forperforming wireless communications using a multi-mode WTRU 102 that maybe configured for simultaneous or near-simultaneous operation oncomponent carriers (CCs) associated with a plurality of radio accesstechnologies (RATs).

Referring to FIG. 10, the representative method 1000 may include, atblock 1010, configuring, in the WTRU 102, a high speed packet access(HSPA) medium access control (MAC) entity and a long term evolution(LTE) MAC entity. At block 1020, a plurality of channels may beconfigured that may be associated with the HSPA and LTE MAC entities.

In certain representative embodiments, the configuring of the HSPA MACentity and the LTE MAC entity may include integrating the HSPA MAC andthe LTE MAC to aggregate data exchanged via HSPA and LTE RATs.

FIG. 11 is a flowchart illustrating another representative method 1100for performing wireless communications using a multi-mode WTRU 102 thatmay be configured to for concurrent operation on component carriers(CCs) associated with a plurality of radio access technologies (RATs).

Referring to FIG. 11, the representative method 1100 may include, atblock 1110, information exchanged on a first CC in accordance with afirst RAT. At block 1120, information may be concurrently exchanged on asecond CC in accordance with a second RAT. At block 1130, theinformation exchanged may be aggregated or segmented via the first andsecond CCs.

In certain representative embodiments, the representative method mayinclude configuring one of: (1) a single radio resource connection tomaintain the exchange of the information on the first and second CCs;(2) a radio resource connection for each CC used to maintain theexchange of the information on the first and second CCs; or (3) a radioresource connection for each RAT used to maintain the exchange of theinformation on the first and second CCs.

In certain representative embodiments, the representative method mayinclude the WTRU 102 sending a block acknowledgment associated with thesecond CC on the first CC to provide a blockacknowledgment/non-acknowledgement indication associated withinformation exchanged on the second CC.

FIG. 12 is a flowchart illustrating a representative method 1200 forperforming wireless communications in a WTRU 102 supporting multi-RATcarrier aggregation (CA).

Referring to FIG. 12, the representative method 1200 may include, atblock 1210, information allocated on a first carrier according to afirst RAT. At block 1220, information may be concurrently allocated on asecond carrier according to a second RAT.

In certain representative embodiments, the first RAT may be one of: (1)long term evolution (LTE); (2) wideband code division multiple access(WCDMA); (3) high speed packet access (HSPA); (4) high speed downlinkpacket access (HSDPA) or (5) high speed uplink packet access (HSUPA).

In certain representative embodiments, the second RAT may be a differentRAT from the first RAT.

FIG. 13 is a flowchart illustrating a further representative method 1300for performing wireless communications using a multi-mode WTRU 102 thatmay be configured for concurrent operation on component carriers (CCs)associated with a plurality of RATs.

Referring to FIG. 13, the representative method 1300 may include, atblock 1310, information allocated on a first CC in accordance with along term evolution (LTE) RAT. At block 1320, information may beconcurrently allocated on a second CC in accordance with a differentRAT.

In certain representative embodiments, a single radio resource control(RRC) connection may be used to control radio resources of the RATssupported concurrently by the WTRU 102.

In certain representative embodiments, the representative method mayinclude the WTRU 102 concurrently using one radio resource control (RRC)connection for each of the plurality of RATs applicable to differentsets of at least one CC.

In certain representative embodiments, the plurality of RATs may operateon the same or different frequencies.

In certain representative embodiments, the representative method mayinclude the WTRU 102 concurrently using one radio resource control (RRC)connection for each of the RATs applicable to different sets of at leastone CC.

FIG. 14 is a flowchart illustrating another representative method 1400for performing wireless communications in a WTRU 102 supportingmulti-RAT CA

Referring to FIG. 14, the representative method 1400 may include, atblock 1410, a first medium access control (MAC) entity configured in theWTRU 102 that may be associated with a first RAT. At block 1420, asecond MAC entity may be configured in the WTRU 102 that may beassociated with a second RAT. At block 1430 a plurality of channels maybe configured that may be associated with the first MAC entity and thesecond MAC entity.

In certain representative embodiments, the first RAT may be long termevolution (LTE) and the second RAT may be one of: (1) wideband codedivision multiple access (WCDMA); (2) high speed packet access (HSPA);(3) high speed downlink packet access (HSDPA); (4) high speed uplinkpacket access (HSUPA); (5) a non-cellular radio access; or (6) a WiFiradio access.

Although features and elements are described above in particularcombinations, one of ordinary skill in the art may appreciate that eachfeature or element can be used alone or in any combination with theother features and elements. In addition, the methods described hereinmay be implemented in a computer program, software, or firmwareincorporated in a computer readable medium for execution by a computeror processor. Examples of non-transitory computer-readable storage mediainclude, but are not limited to, a read only memory (ROM), random accessmemory (RAM), a register, cache memory, semiconductor memory devices,magnetic media such as internal hard disks and removable disks,magneto-optical media, and optical media such as CD-ROM disks, anddigital versatile disks (DVDs). A processor in association with softwaremay be used to implement a radio frequency transceiver for use in aWTRU, UE, terminal, base station, RNC, or any host computer.

Moreover, in the embodiments described above, processing platforms,computing systems, controllers, and other devices containing processorsare noted. These devices may contain at least one Central ProcessingUnit (“CPU”) and memory. In accordance with the practices of personsskilled in the art of computer programming, reference to acts andsymbolic representations of operations or instructions may be performedby the various CPUs and memories. Such acts and operations orinstructions may be referred to as being “executed,” “computer executed”or “CPU executed.”

One of ordinary skill in the art may appreciate that the acts andsymbolically represented operations or instructions include themanipulation of electrical signals by the CPU. An electrical systemrepresents data bits that can cause a resulting transformation orreduction of the electrical signals and the maintenance of data bits atmemory locations in a memory system to thereby reconfigure or otherwisealter the CPU's operation, as well as other processing of signals. Thememory locations where data bits are maintained are physical locationsthat have particular electrical, magnetic, optical, or organicproperties corresponding to or representative of the data bits.

The data bits may also be maintained on a computer readable mediumincluding magnetic disks, optical disks, and any other volatile (e.g.,Random Access Memory (“RAM”)) or non-volatile (“e.g., Read-Only Memory(“ROM”)) mass storage system readable by the CPU. The computer readablemedium may include cooperating or interconnected computer readablemedium, which exist exclusively on the processing system or aredistributed among multiple interconnected processing systems that may belocal or remote to the processing system. It is understood that therepresentative embodiments are not limited to the above-mentionedmemories and that other platforms and memories may support the describedmethods.

No element, act, or instruction used in the description of the presentapplication should be construed as critical or essential to theinvention unless explicitly described as such. Also, as used herein, thearticle “a” is intended to include one or more items. Where only oneitem is intended, the term “one” or similar language is used. Further,the terms “any of” followed by a listing of a plurality of items and/ora plurality of categories of items, as used herein, are intended toinclude “any of,” “any combination of,” “any multiple of,” and/or “anycombination of multiples of” the items and/or the categories of items,individually or in conjunction with other items and/or other categoriesof items. Further, as used herein, the term “set” is intended to includeany number of items, including zero. Further, as used herein, the term“number” is intended to include any number, including zero.

Moreover, the claims should not be read as limited to the describedorder or elements unless stated to that effect. In addition, use of theterm “means” in any claim is intended to invoke 35 U.S.C. § 112, 6, andany claim without the word “means” is not so intended.

Suitable processors include, by way of example, a general purposeprocessor, a special purpose processor, a conventional processor, adigital signal processor (DSP), a plurality of microprocessors, one ormore microprocessors in association with a DSP core, a controller, amicrocontroller, Application Specific Integrated Circuits (ASICs),Application Specific Standard Products (ASSPs); Field Programmable GateArrays (FPGAs) circuits, any other type of integrated circuit (IC),and/or a state machine.

A processor in association with software may be used to implement aradio frequency transceiver for use in a wireless transmit receive unit(WTRU), user equipment (UE), terminal, base station, Mobility ManagementEntity (MME) or Evolved Packet Core (EPC), or any host computer. TheWTRU may be used m conjunction with modules, implemented in hardwareand/or software including a Software Defined Radio (SDR), and othercomponents such as a camera, a video camera module, a videophone, aspeakerphone, a vibration device, a speaker, a microphone, a televisiontransceiver, a hands free headset, a keyboard, a Bluetooth® module, afrequency modulated (FM) radio unit, a Near Field Communication (NFC)Module, a liquid crystal display (LCD) display unit, an organiclight-emitting diode (OLED) display unit, a digital music player, amedia player, a video game player module, an Internet browser, and/orany Wireless Local Area Network (WLAN) or Ultra Wide Band (UWB) module.

Although the invention has been described in terms of communicationsystems, it is contemplated that the systems may be implemented insoftware on microprocessors/general purpose computers (not shown). Incertain embodiments, one or more of the functions of the variouscomponents may be implemented in software that controls a generalpurpose computer.

In addition, although the invention is illustrated and described hereinwith reference to specific embodiments, the invention is not intended tobe limited to the details shown. Rather, various modifications may bemade in the details within the scope and range of equivalents of theclaims and without departing from the invention.

Embodiments

In one embodiment, a method of managing carrier aggregation for amulti-radio access technology (RAT) wireless transmitter/receiver unit(WTRU) comprises receiving, by the WRTU over a primary channelassociated with a RAT of a first type, provisioning information forprovisioning a supplementary channel associated with a RAT of a secondtype; establishing the supplementary channel associated with the RAT ofthe second type based on the received provisioning information; andwirelessly exchanging, by the WRTU, first data associated with acommunication over the primary channel via the RAT of the first type,while wireless exchanging second data associated with the communicationover the supplementary channel via the RAT of the second type.

In one embodiments, the wirelessly exchanging of the second data overthe established supplementary channel includes one of: (1) wirelesslysending the second data over the established supplementary channel; (2)wirelessly receiving the second data over the established supplementarychannel or (3) wirelessly sending and receiving different portions ofthe second data over the established supplementary channel.

In one embodiment, the wirelessly receiving provisioning informationincludes receiving via the primary channel associated with the RAT ofthe first type control information for the primary channel and controlinformation for the supplementary channel.

In one embodiment, the first type of RAT is one of: (1) a wideband codedivision multiple access (WCDMA) RAT; (2) a high speed packet access(HSPA) RAT; (3) a high speed downlink packet access (HSDPA) RAT; (4) ahigh speed uplink packet access (HSUPA) RAT; or (5) a long termevolution (LTE) RAT.

In one embodiment, the second type of RAT is a different one of: (1) theWCDMA RAT; (2) the HSPA RAT; (3) the HSDPA RAT; (4) the HSUPA RAT; (5) aLTE RAT; (6) a non-cellular RAT; or (7) a WiFi RAT.

In one embodiment, the establishing of the supplementary channelassociated with the RAT of the second type includes: determining, fromthe received provisioning information, one or more carrier componentsassociated with the RAT of the second type to be provisioned forwirelessly exchanging the second data over the supplementary channel;and provisioning the supplementary channel using the determined one ormore carrier components.

In one embodiment, the method includes prior to receiving by the WRTUthe provisioning information, establishing the primary channelassociated with the RAT of the first type, and the establishing of thesupplementary channel associated with the RAT of the second typeincludes establishing the supplementary channel using a single radioresource connection to control radio resources of the RATs of the firstand second types.

In one embodiment, the establishing of the single radio resourceconnection includes setting up a radio resource control (RRC)connection.

In one embodiment, the method includes prior to receiving by the WRTUthe provisioning information, establishing the primary channelassociated with the RAT of the first type and the establishing of thesupplementary channel associated with the RAT of the second typeincludes establishing one or more supplementary channels using at leastone respective radio resource connection for each of a plurality ofdifferent RAT types to control radio resources associated with theprimary and one or more supplementary channels supported concurrently bythe WTRU.

In one embodiment, the method includes maintaining the established radioresource connections that are applicable to different sets of one ormore carrier components such that the wirelessly exchanging of the firstdata over the primary channel via the RAT of the first type, whilewireless exchanging second data over the supplementary channel via theRAT of the second type includes exchanging respective portions of thefirst and second data of the communication over different ones of theestablished radio resource via the different sets of carrier components.

In one embodiment, the exchanging of the first data and the second dataincludes operating the WTRU at a first frequency or in a first frequencyband for exchange of the first data and at a second frequency or in asecond frequency band that is the same as or different from the firstfrequency or the first frequency band.

In one embodiment, a method of performing wireless communications usinga multi-mode wireless transmit/receive unit (WTRU) that is configuredfor simultaneous or near-simultaneous operation on component carriers(CCs) associated with a plurality of radio access technologies (RATs)comprises: configuring, in the WTRU, a high speed packet access (HSPA)medium access control (MAC) entity and a long term evolution (LTE) MACentity; and configuring a plurality of channels associated with the HSPAand LTE MAC entities.

In one embodiment, the configuring of the HSPA MAC entity and the LTEMAC entity includes integrating the HSPA MAC and the LTE MAC toaggregate data exchanged via HSPA and LTE RATs.

In one embodiment, a method of performing wireless communications usinga multi-mode wireless transmit/receive unit (WTRU) that is configured tofor concurrent operation on component carriers (CCs) associated with aplurality of radio access technologies (RATs) comprises: exchanginginformation on a first CC in accordance with a first RAT; concurrentlyexchanging information on a second CC in accordance with a second RAT;and aggregating or segmenting the information exchanged via the firstand second CCs.

In one embodiment the method includes configuring one of: (1) a singleradio resource connection to maintain the exchange of the information onthe first and second CCs; a radio resource connection for each CC usedto maintain the exchange of the information on the first and second CCs;or a radio resource connection for each RAT used to maintain theexchange of the information on the first and second CCs.

In one embodiment, the method includes sending, by the WRTU, a blockacknowledgment associated with the second CC on the first CC to providea block acknowledgment/non-acknowledgement indication associatedinformation exchanged on the second CC.

In one embodiment, a method of performing wireless communications in awireless transmit/receive unit (WTRU) supporting multi-radio accesstechnology (RAT) carrier aggregation (CA) comprises: allocatinginformation on a first carrier according to a first RAT; andconcurrently allocating information on a second carrier according to asecond RAT.

In one embodiment, the second RAT is a different RAT than the first RAT.

In one embodiment, a method of performing wireless communications usinga multi-mode wireless transmit/receive unit (WTRU) that is configuredfor concurrent operation on component carriers (CCs) associated with aplurality of radio access technologies (RATs) comprises: allocatinginformation on a first CC in accordance with a long term evolution (LTE)RAT; and concurrently allocating information on a second CC inaccordance with a different RAT.

In one embodiment, a single radio resource control (RRC) connection isused to control radio resources of the RATs supported concurrently bythe WTRU.

In one embodiment, the method includes concurrently using, by the WTRU,one radio resource control (RRC) connection for each of the plurality ofRATs applicable to different sets of at least one CC, wherein theplurality of RATs operates on the same or different frequencies.

In one embodiment, a method of performing wireless communications in awireless transmit/receive unit (WTRU) supporting multi-radio accesstechnology (RAT) carrier aggregation (CA) comprises: configuring a firstmedium access control (MAC) entity in the WTRU that is associated with afirst RAT; configuring a second medium access control (MAC) entity inthe WTRU that is associated with a second RAT; and configuring aplurality of channels associated with the first MAC entity and thesecond MAC entity.

In one embodiment, the first RAT is long term evolution (LTE), and thesecond RAT is one of: (1) wideband code division multiple access(WCDMA); (2) high speed packet access (HSPA);

(3) high speed downlink packet access (HSDPA); (4) high speed uplinkpacket access (HSUPA); (5) a non-cellular radio access; or (6) a WiFiradio access.

In one embodiment, a wireless transmit/receive unit (WTRU) includes: atransmit/receive unit configured to receive over a primary channelassociated with a RAT of a first type, provisioning information forprovisioning a supplementary channel associated with a RAT of a secondtype; and a processor configured to establish the supplementary channelassociated with the RAT of the second type based on the receivedprovisioning information such that the transmit/receive unit wirelesslyexchanges first data associated with a communication over the primarychannel via the RAT of the first type, while wireless exchanging seconddata associated with the communication over the supplementary channelvia the RAT of the second type.

In one embodiment, the transmit/receive unit wirelessly receives, viathe primary channel associated with the RAT of the first type, controlinformation for the primary channel and control information for thesupplementary channel.

In one embodiment, the transmit/receive unit wirelessly exchanges thefirst data using one of: (1) a wideband code division multiple access(WCDMA); (2) a high speed packet access (HSPA);

(3) a high speed downlink packet access (HSDPA); (4) a high speed uplinkpacket access (HSUPA); and/or (5) long term evolution; (LTE) access;

In one embodiment, the transmit/receive unit exchanges the second data,during the exchange of the first data, using at least a different oneof: (1) the WCDMA; (2) the HSPA; (3) the HSDPA;

(4) the HSUPA; (5) the LTE access; (6) a non-cellular access; and/or (7)a WiFi access.

In one embodiment, the processor determines from the receivedprovisioning information one or more carrier components associated withthe RAT of the second type to be provisioned for wirelessly exchangingthe second data over the supplementary channel; and provisions thesupplementary channel using the determined one or more carriercomponents.

In one embodiment, the processor, prior to receiving the provisioninginformation, establishes the primary channel associated with a singleradio resource connection and, after receiving the provisioninginformation, establishes the supplementary channel associated with thesame single radio resource connection of the primary channel to controlradio resources of the RATs of the first and second types.

In one embodiment, the processor, prior to receiving the provisioninginformation, establishes the primary channel associated with a firstradio resource connection and, after receiving the provisioninginformation, establishes the supplementary channel associated with asecond radio resource connection to respectively control radio resourcesof the RATs of the first and second types.

In one embodiment, the processor operates the WTRU at a first frequencyor in a first frequency band for exchange of the first data and at asecond frequency or in a second frequency band that is the same ordifferent from the first frequency or the first frequency band.

In one embodiment, a multi-mode wireless transmit/receive unit (WTRU)for performing wireless communications and configured for concurrentoperation on component carriers (CCs) associated with a plurality ofradio access technologies (RATs), comprises a processor configured forconcurrent operation of a high speed packet access (HSPA) medium accesscontrol (MAC) entity, a long term evolution (LTE) MAC entity; and aplurality of channels associated with the HSPA and LTE MAC entities suchthat the HSPA MAC entity and the LTE MAC entity are configured toaggregate data exchanged via HSPA and LTE RATs.

In one embodiment, a multi-mode wireless transmit/receive unit (WTRU)for performing wireless communications and configured to supportsimultaneous or near-simultaneous operation on component carriers (CCs)associated with a plurality of radio access technologies (RATs),comprises a transmit/receive unit configured to exchange information viaa first CC in accordance with a first RAT and to concurrently exchangeinformation via a second CC in accordance with a second RAT; and aprocessor configured to aggregate or to segment the informationexchanged via the first and second CCs.

In one embodiment, the WTRU is one of: (1) an end user terminal; or anetwork access point.

In one embodiment, a method of managing carrier aggregation for amulti-radio access technology (RAT) wireless transmitter/receiver unit(WTRU) comprises: receiving, by the WRTU over a primary channelassociated with a 3GPP RAT, provisioning information for provisioning asupplementary channel associated with a WiFi RAT; establishing thesupplementary channel associated with theWiFi RAT based on the receivedprovisioning information; and wirelessly exchanging, by the WRTU, firstdata associated with a communication over the primary channel via the3GPP RAT, while wireless exchanging second data associated with thecommunication over the supplementary channel via the 3GPP RAT.

In one embodiment, the receiving of the provisioning informationincludes configuring a 3GPP RRC connection via a 3GPP access point andproviding parameters for accessing a WiFi network associated with theWiFi RAT.

In one embodiment, the providing of the parameters for accessing theWiFi network include: at least one of: (1) a frequency band of the WiFinetwork; (2) a specific channel for the WiFi network; (3) an operationmode for the WiFi network, (4) a Serving Set Identifier (SSID) of theWiFi network; (5) a Basic SSID (BSSID) of a WiFi access point associatedwith the WiFi network; (6) a set of one or more security parameters; or(7) an indication to activate a WiFi transceiver in the WTRU.

In one embodiment, a non-transitory computer readable storage mediumstores program code executable by computer for implementing any method.

1-26. (canceled)
 27. A method of managing a multi-radio accesstechnology (multi-RAT) wireless transmitter/receiver unit (WTRU), themethod comprising: configuring, by the multi-RAT WTRU, a primary radioconnection of a RAT of a first type; receiving, by the multi-RAT WTRUvia the primary radio connection, configuration information to configurea secondary radio connection of a RAT of a second type; configuring, bythe multi-RAT WTRU, the secondary radio connection of the RAT of thesecond type based on the received configuration information of the RATof the second type; and receiving, by the multi-RAT WTRU, controlinformation for the RAT of the second type using the primary radioconnection, wherein: the control information for the secondary radioconnection of the RAT of the second type is received within a protocoldata unit (PDU) of the RRC protocol of the RAT of the first type, andthe control information for the secondary radio connection of the RAT ofthe second type is an information element (IE) according to the RRCprotocol of the second type.
 28. The method of claim 27, wherein the RATof first type is a long-term evolution (LTE) RAT and the RAT of thesecond type is different from the first type of RAT.
 29. The method ofclaim 27, wherein the RAT of the first type is a 3GPP RAT and the RAT ofthe second type is a different 3GPP RAT.
 30. The method of claim 27,further comprising: determining, by the multi-RAT WTRU, that a radiolink failure (RLF) has occurred on the RAT of the second type; andtransmitting, by the multi-RAT WTRU, a message using resources of theRAT of the first type based on the determined RLF.
 31. The method ofclaim 30, wherein the transmitting of the message using resources of theRAT of the first type includes transmitting, via the primary radioconnection, RLF information that is associated with the RLF that hasoccurred on the RAT of the second type.
 32. The method of claim 30,wherein the transmitting of the message includes sending a notificationover the primary radio connection on condition that the RLF has occurredon the secondary radio connection of the RAT of the second type.
 33. Themethod of claim 32, wherein the notification is a layer 2 message or alayer 3 message.
 34. The method of claim 33, further comprising:receiving, via the primary radio connection of the RAT of the firsttype, a message requesting the multi-RAT WTRU to perform a random accessprocedure for the RAT of the second type; initiating, by the multi-RATWTRU, the random access procedure; and receiving, by the multi-RAT WTRUas part of the random access procedure, a random access responseincluding a grant for resources of the RAT of the second type over theprimary radio connection of the RAT of the first type.
 35. The method ofclaim 27, further comprising receiving, by the multi-RAT WTRU, a firstdiscontinuous reception (DRX) configuration associated with the RAT ofthe first type and a second, different DRX configuration associated withthe RAT of the second type.
 36. A multi-radio access technology(multi-RAT) wireless transmitter/receiver unit (WTRU), comprising: aprocessor configured to configure a primary radio connection of a RAT ofa first type; and a wireless transmit/receive unit configured to:receive via the primary radio connection configuration information toconfigure a secondary radio connection of a RAT of a second type, andreceive control information for the RAT of the second type using theprimary radio connection, wherein: the processor is configured toconfigure the secondary radio connection of the RAT of the second typebased on the received configuration information of the RAT of the secondtype, the control information for the secondary radio connection of theRAT of the second type is received within a protocol data unit (PDU) ofthe RRC protocol of the RAT of the first type, and the controlinformation for the secondary radio connection of the RAT of the secondtype is an information element (IE) according to the RRC protocol of thesecond type.
 37. The multi-RAT WTRU of claim 36, wherein the RAT of thefirst type is a long-term evolution (LTE) RAT and the RAT of the secondtype is different from the first type of RAT.
 38. The multi-RAT WTRU ofclaim 36, wherein the RAT of the first type is a 3GPP RAT and the RAT ofthe second type is a different 3GPP RAT.
 39. The multi-RAT WTRU of claim36, wherein the wireless transmit/receive unit is configured totransmit, via the primary radio connection, radio link failure (RLF)information that is associated with a RLF that has occurred on the RATof the second type.
 40. The multi-RAT WTRU of claim 36, wherein thewireless transmit/receive unit is configured to receive, via the primaryradio connection, one or more Protocol Data Units (PDUs) of the RAT ofthe second type.
 41. The multi-RAT WTRU of claim 36, wherein theprocessor is configured to: demultiplex the received control informationfor the RAT of the second type to obtain one or more Protocol Data Units(PDUs) of the RAT of the second type; and pass, by a layer or a sublayerof a protocol stack associated with the RAT of the first type to a layeror a sublayer of a protocol stack associated with the RAT of the secondtype, the obtained one or more PDUs.
 42. The multi-RAT WTRU of claim 36,wherein the wireless transmit/receive unit is configured to send anotification over the primary radio connection on condition that a radiolink failure (RLF) has occurred on the secondary radio connection of theRAT of the second type.
 43. The multi-RAT WTRU of claim 42, wherein thenotification is a layer 2 message or a layer 3 message.
 44. Themulti-RAT WTRU of claim 36, wherein: the wireless transmit/receive unitis configured to receive, via the primary radio connection of the RAT ofthe first type, a message requesting the multi-RAT WTRU to perform arandom access procedure for the RAT of the second type; the processor isconfigured to initiate the random access procedure; and the wirelesstransmit/receive unit is configured to receive as part of the randomaccess procedure, a random access response including a grant forresources of the RAT of the second type over the primary radioconnection of the RAT of the first type.
 45. The multi-RAT WTRU of claim36, wherein the wireless transmit/receive unit is configured to receivea first discontinuous reception (DRX) configuration associated with theRAT of the first type and a second, different DRX configurationassociated with the RAT of the second type.